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Research ArticleThe Effect of Nuclear Elastic Scattering on TemperatureEquilibration Rate of Ions in Fusion Plasma
M Mahdavi1 R Azadifar1 and T Koohrokhi2
1 Physics Department University of Mazandaran PO Box 47415-416 Babolsar Iran2 Physics Department Faculty of Sciences Golestan University Shahid Beheshti Street PO Box 155 Gorgan Iran
Correspondence should be addressed to M Mahdavi mmahdaviumzacir
Received 30 May 2014 Accepted 27 October 2014 Published 17 November 2014
Academic Editor Luis A Anchordoqui
Copyright copy 2014 M Mahdavi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited Thepublication of this article was funded by SCOAP3
A plasma with two different particle types and at different temperatures has been considered so that each type of ion withMaxwell-Boltzmann distribution function is in temperature equilibrium with itself Using the extracted nuclear elastic scattering differentialcross-section from experimental data solving the Boltzmann equation and also taking into account themobility of the backgroundparticles temperature equilibration rate between two different ions in a fusion plasma is calculatedThe results show that at highertemperature differences effect of nuclear elastic scattering is more important in calculating the temperature equilibration rate Theobtained expressions have general form so that they are applicable to each type of particle for background (119887) and each type forprojectile (119901) In this paper for example an equimolar Deuterium-Hydrogen plasma with density 119899 = 5 times 10
25 cmminus3 is chosen inwhich the deuteron is the background particle with temperature (also electron temperature) 119879
119887= 1 keV (usual conditions for a
fusion plasma at the ignition instant) and the proton is the projectile with temperature 119879119901gt 119879119887 These calculations particularly are
very important for ion fast ignition in inertial confinement fusion concept
1 Introduction
In a fusion plasma because of interactions collisions andgain and loss powers we encounter an unstable plasma [12] The thermal equilibrium between charged particles iscrucial for understanding the overall energy balance in afusion plasma where the ignition and burn of the plasmaare strongly temperature dependent [3] Since a plasma iscomposed of charged particles they are affected by Coulombforce in the plasma Coulomb force is a long-range force andthus may also be involved in the short-range collisions andthe long-range collective effects The problem of temperatureequilibration was studied first by Landau [4 5] and Spitzer(LS) [6]TheLSmodel is applicable to dilute hot fully ionizedplasmas where the collisions are weak and binary Recentlythere have been several theoretical and computational workswhich aim to study temperature equilibration [7ndash12] Amongthe theoretical studies Brown Preston and Singleton (BPS)by solving the Boltzmann equation for short-range collisionsand the Lenard-Balescu equation for long-range collective
effects and also considering the quantum corrections haveachieved more accurate results [9] In a hot and densefusion plasma in addition to the Coulomb interactions thenuclear elastic scattering (NES) is able to role via short-rangeinteractions (hard collisions) The effect of the NES on thestopping power of a charged particle has been investigatedin previous studies [13ndash15] It has been indicated that thestopping power due to NES is greater at the higher projectileenergies This fact motivated us to study the effect of NESon thermal equilibration rate for a fusion plasma A fusionplasma is formed from charged particles at high temperaturesin which they interact with each other to achieve balanceIn this paper for the simplest case a plasma with twodifferent ions at different temperatures has been consideredso that each type of ionwithMaxwell-Boltzmann distributionfunction is in temperature equilibrium with itself Herefor example proton at higher temperature is considered asprojectile and deuteron at lower temperature is assumed asbackground By solving the Boltzmann equation and takinginto account the thermal motion of plasma ions the thermal
Hindawi Publishing CorporationAdvances in High Energy PhysicsVolume 2014 Article ID 739491 7 pageshttpdxdoiorg1011552014739491
2 Advances in High Energy Physics
equilibration rate due to NES is calculated The results arecompared with Coulomb calculations and the conditions inwhich each contribution is dominated are discussed
2 Elastic Collision
Consider a projectile with mass 119898119901and velocity k
119901interact-
ing with a background particle with mass 119898119887and velocity k
119887
in laboratory frame (Vectors are written in bold type andnonbold letters indicate quantity magnitude) In an elasticcollision V
119888= (119898
119901k119901+ 119898119887k119887)119872119901119887
is the velocity of thecenter of mass (CM) and relative velocity of the system isk119901119887
= k119901minus k119887 After the collision the projectile and target
velocities consider k1015840119901and k1015840
119887 respectively Therefore k1015840
119901119887=
k1015840119901minus k1015840119887is the relative velocity of two particles after collision
These quantities are related to each other by
k119901= V119888+
119898119887
119872119901119887
k119901119887
k1015840119901= V119888+
119898119887
119872119901119887
k1015840119901119887
(1)
where 119872119901119887
= 119898119901+ 119898119887is the total mass The conservation
laws for linear momentum and kinetic energy in the CMsystem indicate that the relative speeds of the particles donot change before and after collision as a result of an elasticcollision |k
119901119887| = |k1015840
119901119887| = V
119901119887 As a result the magnitude
of the relative velocities remains unchanged and only theangle Θ (scattering angle in CM system) between k
119901119887and
k1015840119901119887
is changed Since the magnitude and direction of CMvelocities (before and after a collision) will not change V
119888
can be selected as the reference Using the above relationsbetween V
119888and k119901119887
velocities the kinetic energy of the pro-jectile is changed as follows
1198641015840
119901minus 119864119901=1
2119898119901(V10158402119901minus V2119901) = 119898
119901119887V119888sdot (k1015840119901119887
minus k119901119887) (2)
where119898119901119887
= 119898119901119898119887119872119901119887is reducedmass of the projectile and
target system If 120593 is the angle betweenV119888and k119901119887 according
to scattering angle in CM system Θ then angle between V119888
and k1015840119901119887
is (120593 minus Θ) The change in kinetic energy of the pro-jectile is equal to
1198641015840
119901minus 119864119901= 119898119901119887119881119888V119901119887(cos120593 (cosΘ minus 1) + sin120593 sinΘ) (3)
Since the scattering in the CM frame is axially symmetricabout the relative speed k
119901119887 transverse components average
is zero in the scattering process and so the second term onthe right of this equation will be removed
3 Temperature Equilibration Rate due toCoulomb Interaction
The problem of temperature equilibration was first addressedby Landau and Spitzer who used the Fokker-Planck equation
to derive an equilibration rate for one ion species temperature119879119901 given another ion species temperature 119879
119887[4ndash6]
119889120576LS119901119887
119889119905= 119862
LS119901119887(119879119901minus 119879119887) (4)
where 119862LS119901119887
is defined as
119862LS119901119887
= minus8
3radic2120587
radic1198981199011198981198871198852
1199011198852
119887119899119901119899119887lnΛLS119901119887
(119898119901119879119887+ 119898119887119879119901)32
(5)
where 119898119901119887
are the ion species masses 119885119901119887
are the ion char-ges and 119899
119901119887are the number densities The LS Coulomb log-
arithm lnΛLS119901119887
is defined as follows
lnΛLS119901119887
= 23 minus ln[
[
119885119901119885119887(119898119901+ 119898119887)
119898119901119879119887+ 119898119887119879119901
(1198991199011198852
119901
119879119901
+1198991198871198852
119887
119879119887
)
12
]
]
(6)
Recently there have been several theoretical and compu-tational works which aim to study temperature equilibration[7ndash9] The computational studies have all been done withclassical molecular dynamics and have focused on temper-ature equilibration in a multi-eV hydrogen plasma [10ndash12]The results of these studies showed that deviations fromLS approach are to be expected even for moderate valuesof lnΛLS
119901119887 Among the theoretical works Brown Preston
and Singleton (BPS) produced an analytic calculation forCoulomb energy exchange processes for a fusion plasma[9 16 17] These precise calculations are accurate to leadingand next-to-leading order in the plasma coupling parameterand to all orders for two-body quantum scattering within theplasma In general the energy density exchange rate betweenthe two charged particles 119901 and 119887 in a plasma can be writtenas follows
119889120576Coul119901119887
119889119905= 119862
Coul119901119887
(119879119887minus 119879119901) (7)
where 119862Coul119901119887
is called the rate coefficient and it can be writtenas a sum of three terms
119862Coul119901119887
= (119862119862
119901119887119878+ 119862119862
119901119887119877) + 119862119876
119901119887 (8)
where the first two arise from classical short and long distancephysics and the latter term arises from short distance two-body quantum diffraction The first term in (8) the short-distance classical scattering contribution reads
119862119862
119901119887119878= minus1198962
1199011198962
119887
(119898119901120573119901119898119887120573119887)12
(119898119901119879119901+ 119898119887119879119887)32
(1
2120587)
32
times [ln1198851199011198851198871198902119870
41198981199011198871198812119901119887
+ 2120574]
(9)
Advances in High Energy Physics 3
where 120574 ≃ 057721 is Euler constant The second termin (8) the long-distance dielectric term that accounts forcollective effects in the plasma is given by
119862119862
119901119887119877=1198962
1199011198962
119887
2120587(119898119901120573119901
2120587)
12
(119898119887120573119887
2120587)
12
times int
infin
minusinfin
119889VV2 exp minus12(119898119901120573119901+ 119898119887120573119887) V2
times119894
2120587
119865 (V)120588total (V)
ln 119865 (V)1198702
(10)
Here 119870 is an arbitrary wave number so that the total resultdoes not depend upon 119870 However sometimes choosing 119870
to be a suitable multiple of the Debye wave number of theplasma simplifies the formula We write the inverse temper-ature of the projectile as 120573
119901= 119879minus1
119901and the plasma species 119887
as 120573119887= 119879minus1
119887 which we measure in energy units Debye wave
number 119896119887of this species is defined by
1198962
119887= 4120587120573
1198871198852
119887119899119887 (11)
where 119899119887is the number density of species 119887 The total Debye
wave number 119896119863is defined by
1198962
119863= sum
119887
1198962
119887 (12)
The function 119865(119906) is related to the leading-order plasmadielectric susceptibility in which it may be expressed in thedispersion form
119865 (119906) = minusint
infin
minusinfin
119889V120588total (V)119906 minus V + 119894120578
(13)
where the limit 120578 rarr 0+ is understood The spectral weight
120588total(V) is defined by
120588total (V) = sum
119887
120588119887(V) (14)
where
120588119887(V) = 119896
2
119887Vradic
120573119887119898119887
2120587exp(minus1
2120573119887119898119887V2) (15)
According to the BPS calculations the general case isobtained by adding a quantum correction which is relatedto the short distance two-body quantum diffraction and tothe classical result Therefore the third term in (8) 119862119876
119901119887is a
coefficient which is calculated from the quantum correctionand is defined as follows
119862119876
119901119887= minus
1
21198962
1199011198962
119887
(119898119901120573119901119898119887120573119887)12
(119898119901119879119901+ 119898119887119879119887)32
(1
2120587)
32
int
infin
0
119889120577 exp(minus1205772)
times [Re120595(1 + 119894120578119901119887
12057712) minus ln
120578119901119887
12057712]
(16)
the strength of the quantum effects associated with the scat-tering of two plasma species 119901 and 119887 is characterized by thedimensionless parameter
120578119901119887
=119885119901119885119887
ℏ119881119901119887
(17)
where the square of the thermal velocity in this expression isdefined by
1198812
119901119887=
119879119901
119898119901
+119879119887
119898119887
(18)
and120595(119911) is the logarithmic derivative of the gamma function
4 Temperature Equilibrium due to NuclearElastic Scattering
Since nuclear force is a short-range force it can only beinvolved in short-range collisions and therefore does notcontribute to long-range cumulative effects of plasma Boltz-mann equations are described generally as short-rangeencounters The equation for the phase-space density 119891
119901(P119901)
of species 119901 is [18]
[120597
120597119905+ k119901sdot nabla]119891
119901(r p119901 119905) = sum
119887
119870119901119887(r p119901 119905) (19)
We suppress the common space and time coordinates r 119905 andwrite the collision term involving species 119887 in the followingform
119870119901119887(r p119901 119905)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℏ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119886V10158402119901minus1
2119898119887V2119887minus1
2119898119886V2119901)
times [119891119887(p1015840119887) 119891119901(p1015840119901) minus 119891119887(p119887) 119891119901(p119901)]
(20)
This relation describes the scattering of the particles ofmasses119898119901and 119898
119887and the scattering from the initial momenta
p119901= 119898119901k119901 p119887= 119898119887k119887to the final momenta p1015840
119901= 119898119901k1015840119901
p1015840119887= 119898119887k1015840119887with the scattering amplitude 119879(119882 119902
2) depending
on the center-of-mass energy 119882 and the squared momen-tum transfer 1199022 It is convenient to employ this quantum-mechanical notation for several reasons It explicitly displaysthe complete kinematical character of a scattering processincluding the detailed balance symmetry Furthermore itshows that the collision term (19) vanishes when all theparticles are in thermal equilibriumwith the generic densities119891(p) sim exp[minus120573119898V22] because of the conservation of energyenforced by the delta function In case we have a spatialuniformity (homogeneity) include the gradient removed
4 Advances in High Energy Physics
from (19) and thus the rate of change of energy is obtainedas follows
119889120576119901119887
119889119905= int
1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
120597119891119901(p119901 119905)
120597119905
= int1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
119870119901119887(p119901)
(21)
Placement of relation (20) in (21) and rate of change of energydensity of species 119901 in collisions with plasma species 119887will bewritten as follows
119889120576119901119887
119889119905
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3(
11990110158402
119901
2119898119901
minus1199012
119901
2119898119901
)
times |119879|2(2120587ℏ)
3119891119887(P119887) 119891119901(P119901) 120575(3)
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(22)
Now in general the cross section for the scattering of par-ticles 119901 and 119887 into a restricted momentum interval Δ is givenby
V119901119887intΔ
119889Ω(119889120590119901119887
119889Ω)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℎ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(23)
We can write (23) in terms of the speed of the center of massV119888and relative speed k
119901119887 We use the conversion 119889k
119901119889k119887=
119895(k119901 k119887V119888 k119901119887)119889V119888119889k119901119887 where (119895(k
119901k119887V119888k119901119887) = 1) is the
Jacobian Using these definitions we find that
119889120576119901119887
119889119905= int
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3119891119887(P119887) 119891119901(P119901) V119901119887
times int119889Ω(119889120590119901119887
119889Ω) [1198641015840
119901minus 119864119901]
(24)
Equation (24) represents the rate of change of energy densityof projectile particles 119901 in collisions with plasma species 119887Now consider the particles distribution functions 119901 and 119887119891119901(p119901) and 119891
119887(p119887) where
119891119895(p119895) = 119899119895(2120587ℏ2120573119895
119898119895
)
32
exp(minus12120573119895119898119895V2119895) (25)
is the Maxwellian distribution function Then temperatureEquilibration rate can be calculated as follows
119889120576NI119901119887
119889119905= 119862
NI119901119887(119879119887minus 119879119901) (26)
where the coefficient 119862NI119901119887
is given by
119862NI119901119887
= minus11989911990111989911988712058712
272
(119898119901119898119887)12
119872119901119887
(119898119901119879119901+ 119898119887119879119887)52
times int
infin
0
1198642
119888119889119864119888exp(minus
119872119901119887
119898119901119879119887+ 119898119887119879119901
119864119888)
times 119868NI(119864119862)
(27)
where the integral
119868NI(119864119862) = int
120587
0
(119889120590
NI119901119887
119889Ω) (cosΘ minus 1) sinΘ119889Θ (28)
and 119864119888
= 12119898119901119887V2119901119887
is the total energy of the projectileand the target is in the center of mass system Extractingof NES differential cross-section from experimental values(119889120590
NI119901119887119889Ω) rate of temperature equilibration is archived It
is seen that (26) when the two types of ion temperatureare equal 119889120576NI
119901119887119889119905 = 0 which indicates the temperature
equilibrium
5 Results and Discussion
Now we will consider the thermal equilibration rate betweenthe proton and deuteron in an equimolar plasma withdensity 119899 = 5 times 10
25 cmminus3 The deuteron is consideredas the background at temperature 119879
119887= 1 keV and the
proton is the projectile at temperature 119879119901 greater than the
background temperature (119879119901
gt 119879119887) It is assumed that
each type of particle is in equilibrium with itself so that theequilibrium is described byMaxwell-Boltzmann distributionfunction The density and temperatures are chosen so thatthe their values are close to initial conditions of an inertialconfinement fusion fuel at ignition moment The thermalequilibration rate due to Coulomb interactions is obtainedfrom (5) and (7) for LS and BPS relations respectively(Figure 1) The portions of singular term (see (9)) regularterm (see (10)) and quantum term (see (16)) of BPS relationare shown separately It is seen that the values obtainedfrom the BPS calculations would give lower values thanLS calculations However the most important point is thatboth equilibration rates are further reduction at the highertemperature differences This event is predictable of coursebecause the Coulomb differential cross section (Rutherfordrsquosdifferential cross section) is proportionalwith the total energyin center of mass system (119864
119862) as 119889120590Coul
119889Ω prop 119864minus2
119862 The total
energy in the center of mass system increases with increasingthe temperature difference between the two ions and thus
Advances in High Energy Physics 5
260
240
220
200
180
160
120
140
100
60
80
40
20
0minus20
0 5 10 15 20 25 30 35 40 45 50 55 60
(Tb minus Tp) (keV)LSBPSBPS-R
BPS-SBPS-Q
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 1 The thermal equilibration rate due to Coulomb interac-tions is obtained from (4) and (7) for LS and BPS relations respec-tively
106
0067MeV
105
133MeV333MeV
104
1066MeV4320MeV100MeV
103
102
101
100
0 20 40 60 80 100 120 140 160 180
Θ (deg)
(d120590
exp dΩ)(d120590
Cou
l dΩ)
Figure 2 The ratio of the experimental differential cross-section(119889exp119901119887
120590119889Ω) to the Coulomb differential cross-section (119889Coul119901119887
120590119889Ω)is plotted versus the scattering angle in the center of mass system(Θ) for different energies 119864
119862 for proton-deuteron elastic scattering
the rate of Coulomb interaction decreases due to reductionof its cross-section
In Figure 2 the ratio of the experimental differentialcross-section (119889exp
119901119887120590119889Ω) to the Coulomb differential cross-
section (119889Coul119901119887
120590119889Ω) is plotted versus the scattering anglein the center of mass system (Θ) for different energies forproton-deuteron elastic scattering The labeled energies in
008
007
006
005
004
003
002
001
000
minus0010 1 2 3 4 5 6 7 8 9 10 11 12
EC (MeV)
INI (E
C)
Figure 3The integral 119868NI(119864119862) (see (28)) versus the total energies in
the center of mass coordinate 119864119862
the figure are the total energy in the center of mass system(119864119862) As can be seen this ratio is different for different
energies and also is associated with fluctuations However ingeneral this ratio is increased more by increasing the energyand this means that the experimental differential cross-section ismore deviated from the Coulomb differential cross-section Deviation increase reflects the growth of the contri-bution of NES differential cross-section (119889NI
119901119887120590119889Ω) at higher
energies (the superscript NI denotes the sum of nuclearand interference terms that for simplicity are called nuclearelastic scattering (NES))
By extracting the NES differential cross-section fromexperimental data (119889NI
119901119887120590119889Ω = 119889
exp119901119887
120590119889Ω minus 119889Coul119901119887
120590119889Ω)the integral 119868NI(119864
119862) (see (28)) can be calculated (Figure 3)
The integral 119868NI(119864119862) is submitted in (27) and the thermal
equilibration rate due toNES can be obtained Figure 4 showsthe thermal equilibration rate due to NES (NI) and Coulombinteraction (LS and BPS) and also the total term that isobtained from sum of nuclear and Coulomb contributions(NI +BPS) It is seen that the thermal equilibration rate due toCoulomb interaction has the main contribution in the lowertemperature differences With increasing temperature theCoulomb interaction contribution decreases and increases inthe share of NES Thus at temperature differences Δ119879 ge
3278MeV the NES is the dominant contribution to thethermal equilibration rate
The rapid development of laser-accelerated ion beamsis developing the ion fast ignition (IFI) scheme in inertialconfinement fusion concept [19] In the IFI scheme anintense laser pulse accelerates an ion beam to multi-MeVtemperatures The accelerated ion beam deposits its energyin the ignition region of fuel pellet that is named ldquohot spotrdquoand provides the required energy for ignition [20 21] Forthis reason the diver ion beam is named ignitor The poweris deposited through an ion beam energy exchange withthe background plasma particles with few-keV temperatures
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
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ThermodynamicsJournal of
2 Advances in High Energy Physics
equilibration rate due to NES is calculated The results arecompared with Coulomb calculations and the conditions inwhich each contribution is dominated are discussed
2 Elastic Collision
Consider a projectile with mass 119898119901and velocity k
119901interact-
ing with a background particle with mass 119898119887and velocity k
119887
in laboratory frame (Vectors are written in bold type andnonbold letters indicate quantity magnitude) In an elasticcollision V
119888= (119898
119901k119901+ 119898119887k119887)119872119901119887
is the velocity of thecenter of mass (CM) and relative velocity of the system isk119901119887
= k119901minus k119887 After the collision the projectile and target
velocities consider k1015840119901and k1015840
119887 respectively Therefore k1015840
119901119887=
k1015840119901minus k1015840119887is the relative velocity of two particles after collision
These quantities are related to each other by
k119901= V119888+
119898119887
119872119901119887
k119901119887
k1015840119901= V119888+
119898119887
119872119901119887
k1015840119901119887
(1)
where 119872119901119887
= 119898119901+ 119898119887is the total mass The conservation
laws for linear momentum and kinetic energy in the CMsystem indicate that the relative speeds of the particles donot change before and after collision as a result of an elasticcollision |k
119901119887| = |k1015840
119901119887| = V
119901119887 As a result the magnitude
of the relative velocities remains unchanged and only theangle Θ (scattering angle in CM system) between k
119901119887and
k1015840119901119887
is changed Since the magnitude and direction of CMvelocities (before and after a collision) will not change V
119888
can be selected as the reference Using the above relationsbetween V
119888and k119901119887
velocities the kinetic energy of the pro-jectile is changed as follows
1198641015840
119901minus 119864119901=1
2119898119901(V10158402119901minus V2119901) = 119898
119901119887V119888sdot (k1015840119901119887
minus k119901119887) (2)
where119898119901119887
= 119898119901119898119887119872119901119887is reducedmass of the projectile and
target system If 120593 is the angle betweenV119888and k119901119887 according
to scattering angle in CM system Θ then angle between V119888
and k1015840119901119887
is (120593 minus Θ) The change in kinetic energy of the pro-jectile is equal to
1198641015840
119901minus 119864119901= 119898119901119887119881119888V119901119887(cos120593 (cosΘ minus 1) + sin120593 sinΘ) (3)
Since the scattering in the CM frame is axially symmetricabout the relative speed k
119901119887 transverse components average
is zero in the scattering process and so the second term onthe right of this equation will be removed
3 Temperature Equilibration Rate due toCoulomb Interaction
The problem of temperature equilibration was first addressedby Landau and Spitzer who used the Fokker-Planck equation
to derive an equilibration rate for one ion species temperature119879119901 given another ion species temperature 119879
119887[4ndash6]
119889120576LS119901119887
119889119905= 119862
LS119901119887(119879119901minus 119879119887) (4)
where 119862LS119901119887
is defined as
119862LS119901119887
= minus8
3radic2120587
radic1198981199011198981198871198852
1199011198852
119887119899119901119899119887lnΛLS119901119887
(119898119901119879119887+ 119898119887119879119901)32
(5)
where 119898119901119887
are the ion species masses 119885119901119887
are the ion char-ges and 119899
119901119887are the number densities The LS Coulomb log-
arithm lnΛLS119901119887
is defined as follows
lnΛLS119901119887
= 23 minus ln[
[
119885119901119885119887(119898119901+ 119898119887)
119898119901119879119887+ 119898119887119879119901
(1198991199011198852
119901
119879119901
+1198991198871198852
119887
119879119887
)
12
]
]
(6)
Recently there have been several theoretical and compu-tational works which aim to study temperature equilibration[7ndash9] The computational studies have all been done withclassical molecular dynamics and have focused on temper-ature equilibration in a multi-eV hydrogen plasma [10ndash12]The results of these studies showed that deviations fromLS approach are to be expected even for moderate valuesof lnΛLS
119901119887 Among the theoretical works Brown Preston
and Singleton (BPS) produced an analytic calculation forCoulomb energy exchange processes for a fusion plasma[9 16 17] These precise calculations are accurate to leadingand next-to-leading order in the plasma coupling parameterand to all orders for two-body quantum scattering within theplasma In general the energy density exchange rate betweenthe two charged particles 119901 and 119887 in a plasma can be writtenas follows
119889120576Coul119901119887
119889119905= 119862
Coul119901119887
(119879119887minus 119879119901) (7)
where 119862Coul119901119887
is called the rate coefficient and it can be writtenas a sum of three terms
119862Coul119901119887
= (119862119862
119901119887119878+ 119862119862
119901119887119877) + 119862119876
119901119887 (8)
where the first two arise from classical short and long distancephysics and the latter term arises from short distance two-body quantum diffraction The first term in (8) the short-distance classical scattering contribution reads
119862119862
119901119887119878= minus1198962
1199011198962
119887
(119898119901120573119901119898119887120573119887)12
(119898119901119879119901+ 119898119887119879119887)32
(1
2120587)
32
times [ln1198851199011198851198871198902119870
41198981199011198871198812119901119887
+ 2120574]
(9)
Advances in High Energy Physics 3
where 120574 ≃ 057721 is Euler constant The second termin (8) the long-distance dielectric term that accounts forcollective effects in the plasma is given by
119862119862
119901119887119877=1198962
1199011198962
119887
2120587(119898119901120573119901
2120587)
12
(119898119887120573119887
2120587)
12
times int
infin
minusinfin
119889VV2 exp minus12(119898119901120573119901+ 119898119887120573119887) V2
times119894
2120587
119865 (V)120588total (V)
ln 119865 (V)1198702
(10)
Here 119870 is an arbitrary wave number so that the total resultdoes not depend upon 119870 However sometimes choosing 119870
to be a suitable multiple of the Debye wave number of theplasma simplifies the formula We write the inverse temper-ature of the projectile as 120573
119901= 119879minus1
119901and the plasma species 119887
as 120573119887= 119879minus1
119887 which we measure in energy units Debye wave
number 119896119887of this species is defined by
1198962
119887= 4120587120573
1198871198852
119887119899119887 (11)
where 119899119887is the number density of species 119887 The total Debye
wave number 119896119863is defined by
1198962
119863= sum
119887
1198962
119887 (12)
The function 119865(119906) is related to the leading-order plasmadielectric susceptibility in which it may be expressed in thedispersion form
119865 (119906) = minusint
infin
minusinfin
119889V120588total (V)119906 minus V + 119894120578
(13)
where the limit 120578 rarr 0+ is understood The spectral weight
120588total(V) is defined by
120588total (V) = sum
119887
120588119887(V) (14)
where
120588119887(V) = 119896
2
119887Vradic
120573119887119898119887
2120587exp(minus1
2120573119887119898119887V2) (15)
According to the BPS calculations the general case isobtained by adding a quantum correction which is relatedto the short distance two-body quantum diffraction and tothe classical result Therefore the third term in (8) 119862119876
119901119887is a
coefficient which is calculated from the quantum correctionand is defined as follows
119862119876
119901119887= minus
1
21198962
1199011198962
119887
(119898119901120573119901119898119887120573119887)12
(119898119901119879119901+ 119898119887119879119887)32
(1
2120587)
32
int
infin
0
119889120577 exp(minus1205772)
times [Re120595(1 + 119894120578119901119887
12057712) minus ln
120578119901119887
12057712]
(16)
the strength of the quantum effects associated with the scat-tering of two plasma species 119901 and 119887 is characterized by thedimensionless parameter
120578119901119887
=119885119901119885119887
ℏ119881119901119887
(17)
where the square of the thermal velocity in this expression isdefined by
1198812
119901119887=
119879119901
119898119901
+119879119887
119898119887
(18)
and120595(119911) is the logarithmic derivative of the gamma function
4 Temperature Equilibrium due to NuclearElastic Scattering
Since nuclear force is a short-range force it can only beinvolved in short-range collisions and therefore does notcontribute to long-range cumulative effects of plasma Boltz-mann equations are described generally as short-rangeencounters The equation for the phase-space density 119891
119901(P119901)
of species 119901 is [18]
[120597
120597119905+ k119901sdot nabla]119891
119901(r p119901 119905) = sum
119887
119870119901119887(r p119901 119905) (19)
We suppress the common space and time coordinates r 119905 andwrite the collision term involving species 119887 in the followingform
119870119901119887(r p119901 119905)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℏ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119886V10158402119901minus1
2119898119887V2119887minus1
2119898119886V2119901)
times [119891119887(p1015840119887) 119891119901(p1015840119901) minus 119891119887(p119887) 119891119901(p119901)]
(20)
This relation describes the scattering of the particles ofmasses119898119901and 119898
119887and the scattering from the initial momenta
p119901= 119898119901k119901 p119887= 119898119887k119887to the final momenta p1015840
119901= 119898119901k1015840119901
p1015840119887= 119898119887k1015840119887with the scattering amplitude 119879(119882 119902
2) depending
on the center-of-mass energy 119882 and the squared momen-tum transfer 1199022 It is convenient to employ this quantum-mechanical notation for several reasons It explicitly displaysthe complete kinematical character of a scattering processincluding the detailed balance symmetry Furthermore itshows that the collision term (19) vanishes when all theparticles are in thermal equilibriumwith the generic densities119891(p) sim exp[minus120573119898V22] because of the conservation of energyenforced by the delta function In case we have a spatialuniformity (homogeneity) include the gradient removed
4 Advances in High Energy Physics
from (19) and thus the rate of change of energy is obtainedas follows
119889120576119901119887
119889119905= int
1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
120597119891119901(p119901 119905)
120597119905
= int1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
119870119901119887(p119901)
(21)
Placement of relation (20) in (21) and rate of change of energydensity of species 119901 in collisions with plasma species 119887will bewritten as follows
119889120576119901119887
119889119905
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3(
11990110158402
119901
2119898119901
minus1199012
119901
2119898119901
)
times |119879|2(2120587ℏ)
3119891119887(P119887) 119891119901(P119901) 120575(3)
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(22)
Now in general the cross section for the scattering of par-ticles 119901 and 119887 into a restricted momentum interval Δ is givenby
V119901119887intΔ
119889Ω(119889120590119901119887
119889Ω)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℎ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(23)
We can write (23) in terms of the speed of the center of massV119888and relative speed k
119901119887 We use the conversion 119889k
119901119889k119887=
119895(k119901 k119887V119888 k119901119887)119889V119888119889k119901119887 where (119895(k
119901k119887V119888k119901119887) = 1) is the
Jacobian Using these definitions we find that
119889120576119901119887
119889119905= int
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3119891119887(P119887) 119891119901(P119901) V119901119887
times int119889Ω(119889120590119901119887
119889Ω) [1198641015840
119901minus 119864119901]
(24)
Equation (24) represents the rate of change of energy densityof projectile particles 119901 in collisions with plasma species 119887Now consider the particles distribution functions 119901 and 119887119891119901(p119901) and 119891
119887(p119887) where
119891119895(p119895) = 119899119895(2120587ℏ2120573119895
119898119895
)
32
exp(minus12120573119895119898119895V2119895) (25)
is the Maxwellian distribution function Then temperatureEquilibration rate can be calculated as follows
119889120576NI119901119887
119889119905= 119862
NI119901119887(119879119887minus 119879119901) (26)
where the coefficient 119862NI119901119887
is given by
119862NI119901119887
= minus11989911990111989911988712058712
272
(119898119901119898119887)12
119872119901119887
(119898119901119879119901+ 119898119887119879119887)52
times int
infin
0
1198642
119888119889119864119888exp(minus
119872119901119887
119898119901119879119887+ 119898119887119879119901
119864119888)
times 119868NI(119864119862)
(27)
where the integral
119868NI(119864119862) = int
120587
0
(119889120590
NI119901119887
119889Ω) (cosΘ minus 1) sinΘ119889Θ (28)
and 119864119888
= 12119898119901119887V2119901119887
is the total energy of the projectileand the target is in the center of mass system Extractingof NES differential cross-section from experimental values(119889120590
NI119901119887119889Ω) rate of temperature equilibration is archived It
is seen that (26) when the two types of ion temperatureare equal 119889120576NI
119901119887119889119905 = 0 which indicates the temperature
equilibrium
5 Results and Discussion
Now we will consider the thermal equilibration rate betweenthe proton and deuteron in an equimolar plasma withdensity 119899 = 5 times 10
25 cmminus3 The deuteron is consideredas the background at temperature 119879
119887= 1 keV and the
proton is the projectile at temperature 119879119901 greater than the
background temperature (119879119901
gt 119879119887) It is assumed that
each type of particle is in equilibrium with itself so that theequilibrium is described byMaxwell-Boltzmann distributionfunction The density and temperatures are chosen so thatthe their values are close to initial conditions of an inertialconfinement fusion fuel at ignition moment The thermalequilibration rate due to Coulomb interactions is obtainedfrom (5) and (7) for LS and BPS relations respectively(Figure 1) The portions of singular term (see (9)) regularterm (see (10)) and quantum term (see (16)) of BPS relationare shown separately It is seen that the values obtainedfrom the BPS calculations would give lower values thanLS calculations However the most important point is thatboth equilibration rates are further reduction at the highertemperature differences This event is predictable of coursebecause the Coulomb differential cross section (Rutherfordrsquosdifferential cross section) is proportionalwith the total energyin center of mass system (119864
119862) as 119889120590Coul
119889Ω prop 119864minus2
119862 The total
energy in the center of mass system increases with increasingthe temperature difference between the two ions and thus
Advances in High Energy Physics 5
260
240
220
200
180
160
120
140
100
60
80
40
20
0minus20
0 5 10 15 20 25 30 35 40 45 50 55 60
(Tb minus Tp) (keV)LSBPSBPS-R
BPS-SBPS-Q
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 1 The thermal equilibration rate due to Coulomb interac-tions is obtained from (4) and (7) for LS and BPS relations respec-tively
106
0067MeV
105
133MeV333MeV
104
1066MeV4320MeV100MeV
103
102
101
100
0 20 40 60 80 100 120 140 160 180
Θ (deg)
(d120590
exp dΩ)(d120590
Cou
l dΩ)
Figure 2 The ratio of the experimental differential cross-section(119889exp119901119887
120590119889Ω) to the Coulomb differential cross-section (119889Coul119901119887
120590119889Ω)is plotted versus the scattering angle in the center of mass system(Θ) for different energies 119864
119862 for proton-deuteron elastic scattering
the rate of Coulomb interaction decreases due to reductionof its cross-section
In Figure 2 the ratio of the experimental differentialcross-section (119889exp
119901119887120590119889Ω) to the Coulomb differential cross-
section (119889Coul119901119887
120590119889Ω) is plotted versus the scattering anglein the center of mass system (Θ) for different energies forproton-deuteron elastic scattering The labeled energies in
008
007
006
005
004
003
002
001
000
minus0010 1 2 3 4 5 6 7 8 9 10 11 12
EC (MeV)
INI (E
C)
Figure 3The integral 119868NI(119864119862) (see (28)) versus the total energies in
the center of mass coordinate 119864119862
the figure are the total energy in the center of mass system(119864119862) As can be seen this ratio is different for different
energies and also is associated with fluctuations However ingeneral this ratio is increased more by increasing the energyand this means that the experimental differential cross-section ismore deviated from the Coulomb differential cross-section Deviation increase reflects the growth of the contri-bution of NES differential cross-section (119889NI
119901119887120590119889Ω) at higher
energies (the superscript NI denotes the sum of nuclearand interference terms that for simplicity are called nuclearelastic scattering (NES))
By extracting the NES differential cross-section fromexperimental data (119889NI
119901119887120590119889Ω = 119889
exp119901119887
120590119889Ω minus 119889Coul119901119887
120590119889Ω)the integral 119868NI(119864
119862) (see (28)) can be calculated (Figure 3)
The integral 119868NI(119864119862) is submitted in (27) and the thermal
equilibration rate due toNES can be obtained Figure 4 showsthe thermal equilibration rate due to NES (NI) and Coulombinteraction (LS and BPS) and also the total term that isobtained from sum of nuclear and Coulomb contributions(NI +BPS) It is seen that the thermal equilibration rate due toCoulomb interaction has the main contribution in the lowertemperature differences With increasing temperature theCoulomb interaction contribution decreases and increases inthe share of NES Thus at temperature differences Δ119879 ge
3278MeV the NES is the dominant contribution to thethermal equilibration rate
The rapid development of laser-accelerated ion beamsis developing the ion fast ignition (IFI) scheme in inertialconfinement fusion concept [19] In the IFI scheme anintense laser pulse accelerates an ion beam to multi-MeVtemperatures The accelerated ion beam deposits its energyin the ignition region of fuel pellet that is named ldquohot spotrdquoand provides the required energy for ignition [20 21] Forthis reason the diver ion beam is named ignitor The poweris deposited through an ion beam energy exchange withthe background plasma particles with few-keV temperatures
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
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GravityJournal of
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AstrophysicsJournal of
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Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
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PhotonicsJournal of
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Journal of
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ThermodynamicsJournal of
Advances in High Energy Physics 3
where 120574 ≃ 057721 is Euler constant The second termin (8) the long-distance dielectric term that accounts forcollective effects in the plasma is given by
119862119862
119901119887119877=1198962
1199011198962
119887
2120587(119898119901120573119901
2120587)
12
(119898119887120573119887
2120587)
12
times int
infin
minusinfin
119889VV2 exp minus12(119898119901120573119901+ 119898119887120573119887) V2
times119894
2120587
119865 (V)120588total (V)
ln 119865 (V)1198702
(10)
Here 119870 is an arbitrary wave number so that the total resultdoes not depend upon 119870 However sometimes choosing 119870
to be a suitable multiple of the Debye wave number of theplasma simplifies the formula We write the inverse temper-ature of the projectile as 120573
119901= 119879minus1
119901and the plasma species 119887
as 120573119887= 119879minus1
119887 which we measure in energy units Debye wave
number 119896119887of this species is defined by
1198962
119887= 4120587120573
1198871198852
119887119899119887 (11)
where 119899119887is the number density of species 119887 The total Debye
wave number 119896119863is defined by
1198962
119863= sum
119887
1198962
119887 (12)
The function 119865(119906) is related to the leading-order plasmadielectric susceptibility in which it may be expressed in thedispersion form
119865 (119906) = minusint
infin
minusinfin
119889V120588total (V)119906 minus V + 119894120578
(13)
where the limit 120578 rarr 0+ is understood The spectral weight
120588total(V) is defined by
120588total (V) = sum
119887
120588119887(V) (14)
where
120588119887(V) = 119896
2
119887Vradic
120573119887119898119887
2120587exp(minus1
2120573119887119898119887V2) (15)
According to the BPS calculations the general case isobtained by adding a quantum correction which is relatedto the short distance two-body quantum diffraction and tothe classical result Therefore the third term in (8) 119862119876
119901119887is a
coefficient which is calculated from the quantum correctionand is defined as follows
119862119876
119901119887= minus
1
21198962
1199011198962
119887
(119898119901120573119901119898119887120573119887)12
(119898119901119879119901+ 119898119887119879119887)32
(1
2120587)
32
int
infin
0
119889120577 exp(minus1205772)
times [Re120595(1 + 119894120578119901119887
12057712) minus ln
120578119901119887
12057712]
(16)
the strength of the quantum effects associated with the scat-tering of two plasma species 119901 and 119887 is characterized by thedimensionless parameter
120578119901119887
=119885119901119885119887
ℏ119881119901119887
(17)
where the square of the thermal velocity in this expression isdefined by
1198812
119901119887=
119879119901
119898119901
+119879119887
119898119887
(18)
and120595(119911) is the logarithmic derivative of the gamma function
4 Temperature Equilibrium due to NuclearElastic Scattering
Since nuclear force is a short-range force it can only beinvolved in short-range collisions and therefore does notcontribute to long-range cumulative effects of plasma Boltz-mann equations are described generally as short-rangeencounters The equation for the phase-space density 119891
119901(P119901)
of species 119901 is [18]
[120597
120597119905+ k119901sdot nabla]119891
119901(r p119901 119905) = sum
119887
119870119901119887(r p119901 119905) (19)
We suppress the common space and time coordinates r 119905 andwrite the collision term involving species 119887 in the followingform
119870119901119887(r p119901 119905)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℏ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119886V10158402119901minus1
2119898119887V2119887minus1
2119898119886V2119901)
times [119891119887(p1015840119887) 119891119901(p1015840119901) minus 119891119887(p119887) 119891119901(p119901)]
(20)
This relation describes the scattering of the particles ofmasses119898119901and 119898
119887and the scattering from the initial momenta
p119901= 119898119901k119901 p119887= 119898119887k119887to the final momenta p1015840
119901= 119898119901k1015840119901
p1015840119887= 119898119887k1015840119887with the scattering amplitude 119879(119882 119902
2) depending
on the center-of-mass energy 119882 and the squared momen-tum transfer 1199022 It is convenient to employ this quantum-mechanical notation for several reasons It explicitly displaysthe complete kinematical character of a scattering processincluding the detailed balance symmetry Furthermore itshows that the collision term (19) vanishes when all theparticles are in thermal equilibriumwith the generic densities119891(p) sim exp[minus120573119898V22] because of the conservation of energyenforced by the delta function In case we have a spatialuniformity (homogeneity) include the gradient removed
4 Advances in High Energy Physics
from (19) and thus the rate of change of energy is obtainedas follows
119889120576119901119887
119889119905= int
1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
120597119891119901(p119901 119905)
120597119905
= int1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
119870119901119887(p119901)
(21)
Placement of relation (20) in (21) and rate of change of energydensity of species 119901 in collisions with plasma species 119887will bewritten as follows
119889120576119901119887
119889119905
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3(
11990110158402
119901
2119898119901
minus1199012
119901
2119898119901
)
times |119879|2(2120587ℏ)
3119891119887(P119887) 119891119901(P119901) 120575(3)
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(22)
Now in general the cross section for the scattering of par-ticles 119901 and 119887 into a restricted momentum interval Δ is givenby
V119901119887intΔ
119889Ω(119889120590119901119887
119889Ω)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℎ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(23)
We can write (23) in terms of the speed of the center of massV119888and relative speed k
119901119887 We use the conversion 119889k
119901119889k119887=
119895(k119901 k119887V119888 k119901119887)119889V119888119889k119901119887 where (119895(k
119901k119887V119888k119901119887) = 1) is the
Jacobian Using these definitions we find that
119889120576119901119887
119889119905= int
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3119891119887(P119887) 119891119901(P119901) V119901119887
times int119889Ω(119889120590119901119887
119889Ω) [1198641015840
119901minus 119864119901]
(24)
Equation (24) represents the rate of change of energy densityof projectile particles 119901 in collisions with plasma species 119887Now consider the particles distribution functions 119901 and 119887119891119901(p119901) and 119891
119887(p119887) where
119891119895(p119895) = 119899119895(2120587ℏ2120573119895
119898119895
)
32
exp(minus12120573119895119898119895V2119895) (25)
is the Maxwellian distribution function Then temperatureEquilibration rate can be calculated as follows
119889120576NI119901119887
119889119905= 119862
NI119901119887(119879119887minus 119879119901) (26)
where the coefficient 119862NI119901119887
is given by
119862NI119901119887
= minus11989911990111989911988712058712
272
(119898119901119898119887)12
119872119901119887
(119898119901119879119901+ 119898119887119879119887)52
times int
infin
0
1198642
119888119889119864119888exp(minus
119872119901119887
119898119901119879119887+ 119898119887119879119901
119864119888)
times 119868NI(119864119862)
(27)
where the integral
119868NI(119864119862) = int
120587
0
(119889120590
NI119901119887
119889Ω) (cosΘ minus 1) sinΘ119889Θ (28)
and 119864119888
= 12119898119901119887V2119901119887
is the total energy of the projectileand the target is in the center of mass system Extractingof NES differential cross-section from experimental values(119889120590
NI119901119887119889Ω) rate of temperature equilibration is archived It
is seen that (26) when the two types of ion temperatureare equal 119889120576NI
119901119887119889119905 = 0 which indicates the temperature
equilibrium
5 Results and Discussion
Now we will consider the thermal equilibration rate betweenthe proton and deuteron in an equimolar plasma withdensity 119899 = 5 times 10
25 cmminus3 The deuteron is consideredas the background at temperature 119879
119887= 1 keV and the
proton is the projectile at temperature 119879119901 greater than the
background temperature (119879119901
gt 119879119887) It is assumed that
each type of particle is in equilibrium with itself so that theequilibrium is described byMaxwell-Boltzmann distributionfunction The density and temperatures are chosen so thatthe their values are close to initial conditions of an inertialconfinement fusion fuel at ignition moment The thermalequilibration rate due to Coulomb interactions is obtainedfrom (5) and (7) for LS and BPS relations respectively(Figure 1) The portions of singular term (see (9)) regularterm (see (10)) and quantum term (see (16)) of BPS relationare shown separately It is seen that the values obtainedfrom the BPS calculations would give lower values thanLS calculations However the most important point is thatboth equilibration rates are further reduction at the highertemperature differences This event is predictable of coursebecause the Coulomb differential cross section (Rutherfordrsquosdifferential cross section) is proportionalwith the total energyin center of mass system (119864
119862) as 119889120590Coul
119889Ω prop 119864minus2
119862 The total
energy in the center of mass system increases with increasingthe temperature difference between the two ions and thus
Advances in High Energy Physics 5
260
240
220
200
180
160
120
140
100
60
80
40
20
0minus20
0 5 10 15 20 25 30 35 40 45 50 55 60
(Tb minus Tp) (keV)LSBPSBPS-R
BPS-SBPS-Q
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 1 The thermal equilibration rate due to Coulomb interac-tions is obtained from (4) and (7) for LS and BPS relations respec-tively
106
0067MeV
105
133MeV333MeV
104
1066MeV4320MeV100MeV
103
102
101
100
0 20 40 60 80 100 120 140 160 180
Θ (deg)
(d120590
exp dΩ)(d120590
Cou
l dΩ)
Figure 2 The ratio of the experimental differential cross-section(119889exp119901119887
120590119889Ω) to the Coulomb differential cross-section (119889Coul119901119887
120590119889Ω)is plotted versus the scattering angle in the center of mass system(Θ) for different energies 119864
119862 for proton-deuteron elastic scattering
the rate of Coulomb interaction decreases due to reductionof its cross-section
In Figure 2 the ratio of the experimental differentialcross-section (119889exp
119901119887120590119889Ω) to the Coulomb differential cross-
section (119889Coul119901119887
120590119889Ω) is plotted versus the scattering anglein the center of mass system (Θ) for different energies forproton-deuteron elastic scattering The labeled energies in
008
007
006
005
004
003
002
001
000
minus0010 1 2 3 4 5 6 7 8 9 10 11 12
EC (MeV)
INI (E
C)
Figure 3The integral 119868NI(119864119862) (see (28)) versus the total energies in
the center of mass coordinate 119864119862
the figure are the total energy in the center of mass system(119864119862) As can be seen this ratio is different for different
energies and also is associated with fluctuations However ingeneral this ratio is increased more by increasing the energyand this means that the experimental differential cross-section ismore deviated from the Coulomb differential cross-section Deviation increase reflects the growth of the contri-bution of NES differential cross-section (119889NI
119901119887120590119889Ω) at higher
energies (the superscript NI denotes the sum of nuclearand interference terms that for simplicity are called nuclearelastic scattering (NES))
By extracting the NES differential cross-section fromexperimental data (119889NI
119901119887120590119889Ω = 119889
exp119901119887
120590119889Ω minus 119889Coul119901119887
120590119889Ω)the integral 119868NI(119864
119862) (see (28)) can be calculated (Figure 3)
The integral 119868NI(119864119862) is submitted in (27) and the thermal
equilibration rate due toNES can be obtained Figure 4 showsthe thermal equilibration rate due to NES (NI) and Coulombinteraction (LS and BPS) and also the total term that isobtained from sum of nuclear and Coulomb contributions(NI +BPS) It is seen that the thermal equilibration rate due toCoulomb interaction has the main contribution in the lowertemperature differences With increasing temperature theCoulomb interaction contribution decreases and increases inthe share of NES Thus at temperature differences Δ119879 ge
3278MeV the NES is the dominant contribution to thethermal equilibration rate
The rapid development of laser-accelerated ion beamsis developing the ion fast ignition (IFI) scheme in inertialconfinement fusion concept [19] In the IFI scheme anintense laser pulse accelerates an ion beam to multi-MeVtemperatures The accelerated ion beam deposits its energyin the ignition region of fuel pellet that is named ldquohot spotrdquoand provides the required energy for ignition [20 21] Forthis reason the diver ion beam is named ignitor The poweris deposited through an ion beam energy exchange withthe background plasma particles with few-keV temperatures
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
4 Advances in High Energy Physics
from (19) and thus the rate of change of energy is obtainedas follows
119889120576119901119887
119889119905= int
1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
120597119891119901(p119901 119905)
120597119905
= int1198893p119901
(2120587ℏ)3
1199012
119901
2119898119901
119870119901119887(p119901)
(21)
Placement of relation (20) in (21) and rate of change of energydensity of species 119901 in collisions with plasma species 119887will bewritten as follows
119889120576119901119887
119889119905
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3(
11990110158402
119901
2119898119901
minus1199012
119901
2119898119901
)
times |119879|2(2120587ℏ)
3119891119887(P119887) 119891119901(P119901) 120575(3)
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(22)
Now in general the cross section for the scattering of par-ticles 119901 and 119887 into a restricted momentum interval Δ is givenby
V119901119887intΔ
119889Ω(119889120590119901119887
119889Ω)
= int1198893p1015840119887
(2120587ℏ)3
1198893p1015840119901
(2120587ℏ)3
10038161003816100381610038161003816119879 (119882 119902
2)10038161003816100381610038161003816
2
(2120587ℎ)31205753
times (p1015840119887+ p1015840119901minus p119887minus p119901) (2120587ℏ) 120575
times (1
2119898119887V10158402119887+1
2119898119901V10158402119901minus1
2119898119887V2119887minus1
2119898119901V2119901)
(23)
We can write (23) in terms of the speed of the center of massV119888and relative speed k
119901119887 We use the conversion 119889k
119901119889k119887=
119895(k119901 k119887V119888 k119901119887)119889V119888119889k119901119887 where (119895(k
119901k119887V119888k119901119887) = 1) is the
Jacobian Using these definitions we find that
119889120576119901119887
119889119905= int
1198893p119887
(2120587ℏ)3
1198893p119901
(2120587ℏ)3119891119887(P119887) 119891119901(P119901) V119901119887
times int119889Ω(119889120590119901119887
119889Ω) [1198641015840
119901minus 119864119901]
(24)
Equation (24) represents the rate of change of energy densityof projectile particles 119901 in collisions with plasma species 119887Now consider the particles distribution functions 119901 and 119887119891119901(p119901) and 119891
119887(p119887) where
119891119895(p119895) = 119899119895(2120587ℏ2120573119895
119898119895
)
32
exp(minus12120573119895119898119895V2119895) (25)
is the Maxwellian distribution function Then temperatureEquilibration rate can be calculated as follows
119889120576NI119901119887
119889119905= 119862
NI119901119887(119879119887minus 119879119901) (26)
where the coefficient 119862NI119901119887
is given by
119862NI119901119887
= minus11989911990111989911988712058712
272
(119898119901119898119887)12
119872119901119887
(119898119901119879119901+ 119898119887119879119887)52
times int
infin
0
1198642
119888119889119864119888exp(minus
119872119901119887
119898119901119879119887+ 119898119887119879119901
119864119888)
times 119868NI(119864119862)
(27)
where the integral
119868NI(119864119862) = int
120587
0
(119889120590
NI119901119887
119889Ω) (cosΘ minus 1) sinΘ119889Θ (28)
and 119864119888
= 12119898119901119887V2119901119887
is the total energy of the projectileand the target is in the center of mass system Extractingof NES differential cross-section from experimental values(119889120590
NI119901119887119889Ω) rate of temperature equilibration is archived It
is seen that (26) when the two types of ion temperatureare equal 119889120576NI
119901119887119889119905 = 0 which indicates the temperature
equilibrium
5 Results and Discussion
Now we will consider the thermal equilibration rate betweenthe proton and deuteron in an equimolar plasma withdensity 119899 = 5 times 10
25 cmminus3 The deuteron is consideredas the background at temperature 119879
119887= 1 keV and the
proton is the projectile at temperature 119879119901 greater than the
background temperature (119879119901
gt 119879119887) It is assumed that
each type of particle is in equilibrium with itself so that theequilibrium is described byMaxwell-Boltzmann distributionfunction The density and temperatures are chosen so thatthe their values are close to initial conditions of an inertialconfinement fusion fuel at ignition moment The thermalequilibration rate due to Coulomb interactions is obtainedfrom (5) and (7) for LS and BPS relations respectively(Figure 1) The portions of singular term (see (9)) regularterm (see (10)) and quantum term (see (16)) of BPS relationare shown separately It is seen that the values obtainedfrom the BPS calculations would give lower values thanLS calculations However the most important point is thatboth equilibration rates are further reduction at the highertemperature differences This event is predictable of coursebecause the Coulomb differential cross section (Rutherfordrsquosdifferential cross section) is proportionalwith the total energyin center of mass system (119864
119862) as 119889120590Coul
119889Ω prop 119864minus2
119862 The total
energy in the center of mass system increases with increasingthe temperature difference between the two ions and thus
Advances in High Energy Physics 5
260
240
220
200
180
160
120
140
100
60
80
40
20
0minus20
0 5 10 15 20 25 30 35 40 45 50 55 60
(Tb minus Tp) (keV)LSBPSBPS-R
BPS-SBPS-Q
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 1 The thermal equilibration rate due to Coulomb interac-tions is obtained from (4) and (7) for LS and BPS relations respec-tively
106
0067MeV
105
133MeV333MeV
104
1066MeV4320MeV100MeV
103
102
101
100
0 20 40 60 80 100 120 140 160 180
Θ (deg)
(d120590
exp dΩ)(d120590
Cou
l dΩ)
Figure 2 The ratio of the experimental differential cross-section(119889exp119901119887
120590119889Ω) to the Coulomb differential cross-section (119889Coul119901119887
120590119889Ω)is plotted versus the scattering angle in the center of mass system(Θ) for different energies 119864
119862 for proton-deuteron elastic scattering
the rate of Coulomb interaction decreases due to reductionof its cross-section
In Figure 2 the ratio of the experimental differentialcross-section (119889exp
119901119887120590119889Ω) to the Coulomb differential cross-
section (119889Coul119901119887
120590119889Ω) is plotted versus the scattering anglein the center of mass system (Θ) for different energies forproton-deuteron elastic scattering The labeled energies in
008
007
006
005
004
003
002
001
000
minus0010 1 2 3 4 5 6 7 8 9 10 11 12
EC (MeV)
INI (E
C)
Figure 3The integral 119868NI(119864119862) (see (28)) versus the total energies in
the center of mass coordinate 119864119862
the figure are the total energy in the center of mass system(119864119862) As can be seen this ratio is different for different
energies and also is associated with fluctuations However ingeneral this ratio is increased more by increasing the energyand this means that the experimental differential cross-section ismore deviated from the Coulomb differential cross-section Deviation increase reflects the growth of the contri-bution of NES differential cross-section (119889NI
119901119887120590119889Ω) at higher
energies (the superscript NI denotes the sum of nuclearand interference terms that for simplicity are called nuclearelastic scattering (NES))
By extracting the NES differential cross-section fromexperimental data (119889NI
119901119887120590119889Ω = 119889
exp119901119887
120590119889Ω minus 119889Coul119901119887
120590119889Ω)the integral 119868NI(119864
119862) (see (28)) can be calculated (Figure 3)
The integral 119868NI(119864119862) is submitted in (27) and the thermal
equilibration rate due toNES can be obtained Figure 4 showsthe thermal equilibration rate due to NES (NI) and Coulombinteraction (LS and BPS) and also the total term that isobtained from sum of nuclear and Coulomb contributions(NI +BPS) It is seen that the thermal equilibration rate due toCoulomb interaction has the main contribution in the lowertemperature differences With increasing temperature theCoulomb interaction contribution decreases and increases inthe share of NES Thus at temperature differences Δ119879 ge
3278MeV the NES is the dominant contribution to thethermal equilibration rate
The rapid development of laser-accelerated ion beamsis developing the ion fast ignition (IFI) scheme in inertialconfinement fusion concept [19] In the IFI scheme anintense laser pulse accelerates an ion beam to multi-MeVtemperatures The accelerated ion beam deposits its energyin the ignition region of fuel pellet that is named ldquohot spotrdquoand provides the required energy for ignition [20 21] Forthis reason the diver ion beam is named ignitor The poweris deposited through an ion beam energy exchange withthe background plasma particles with few-keV temperatures
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Advances in High Energy Physics 5
260
240
220
200
180
160
120
140
100
60
80
40
20
0minus20
0 5 10 15 20 25 30 35 40 45 50 55 60
(Tb minus Tp) (keV)LSBPSBPS-R
BPS-SBPS-Q
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 1 The thermal equilibration rate due to Coulomb interac-tions is obtained from (4) and (7) for LS and BPS relations respec-tively
106
0067MeV
105
133MeV333MeV
104
1066MeV4320MeV100MeV
103
102
101
100
0 20 40 60 80 100 120 140 160 180
Θ (deg)
(d120590
exp dΩ)(d120590
Cou
l dΩ)
Figure 2 The ratio of the experimental differential cross-section(119889exp119901119887
120590119889Ω) to the Coulomb differential cross-section (119889Coul119901119887
120590119889Ω)is plotted versus the scattering angle in the center of mass system(Θ) for different energies 119864
119862 for proton-deuteron elastic scattering
the rate of Coulomb interaction decreases due to reductionof its cross-section
In Figure 2 the ratio of the experimental differentialcross-section (119889exp
119901119887120590119889Ω) to the Coulomb differential cross-
section (119889Coul119901119887
120590119889Ω) is plotted versus the scattering anglein the center of mass system (Θ) for different energies forproton-deuteron elastic scattering The labeled energies in
008
007
006
005
004
003
002
001
000
minus0010 1 2 3 4 5 6 7 8 9 10 11 12
EC (MeV)
INI (E
C)
Figure 3The integral 119868NI(119864119862) (see (28)) versus the total energies in
the center of mass coordinate 119864119862
the figure are the total energy in the center of mass system(119864119862) As can be seen this ratio is different for different
energies and also is associated with fluctuations However ingeneral this ratio is increased more by increasing the energyand this means that the experimental differential cross-section ismore deviated from the Coulomb differential cross-section Deviation increase reflects the growth of the contri-bution of NES differential cross-section (119889NI
119901119887120590119889Ω) at higher
energies (the superscript NI denotes the sum of nuclearand interference terms that for simplicity are called nuclearelastic scattering (NES))
By extracting the NES differential cross-section fromexperimental data (119889NI
119901119887120590119889Ω = 119889
exp119901119887
120590119889Ω minus 119889Coul119901119887
120590119889Ω)the integral 119868NI(119864
119862) (see (28)) can be calculated (Figure 3)
The integral 119868NI(119864119862) is submitted in (27) and the thermal
equilibration rate due toNES can be obtained Figure 4 showsthe thermal equilibration rate due to NES (NI) and Coulombinteraction (LS and BPS) and also the total term that isobtained from sum of nuclear and Coulomb contributions(NI +BPS) It is seen that the thermal equilibration rate due toCoulomb interaction has the main contribution in the lowertemperature differences With increasing temperature theCoulomb interaction contribution decreases and increases inthe share of NES Thus at temperature differences Δ119879 ge
3278MeV the NES is the dominant contribution to thethermal equilibration rate
The rapid development of laser-accelerated ion beamsis developing the ion fast ignition (IFI) scheme in inertialconfinement fusion concept [19] In the IFI scheme anintense laser pulse accelerates an ion beam to multi-MeVtemperatures The accelerated ion beam deposits its energyin the ignition region of fuel pellet that is named ldquohot spotrdquoand provides the required energy for ignition [20 21] Forthis reason the diver ion beam is named ignitor The poweris deposited through an ion beam energy exchange withthe background plasma particles with few-keV temperatures
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
6 Advances in High Energy Physics
70
65
60
55
50
45
40
35
30
25
20
15
10
5 3278 (MeV)
20 22 24 26 28 30 32 34 36 38 40
LSBPS
NIBPS + NI
(Tb minus Tp) (MeV)
0
(d120576 pbdt)
n(k
eV p
sminus1 )
Figure 4 The thermal equilibration rate due to NES (NI) andCoulomb interaction (LS and BPS) and also the total term that isobtained from the sum of nuclear and Coulomb contributions (NI +BPS)
In the energy exchange process some of the ion beam energyis delivered to the plasma ions and another part of energy isdelivered to the plasma electronsThe electrons are the sourceof power loss in a fusion plasma that it is better to be kept atlow temperature At the high temperature difference (multi-MeV) between ion beam and background plasma particlesthe rate of energy exchange via Coulomb interaction isreduced and in turn the rate of energy exchange via NES isincreased The NES causes the ion temperature to be furtherincreased resulting in reduced power loss
The laser-accelerated ion beams can be produced withdifferent distribution functions such as exponential Max-wellian and quasimonoenergy distribution functions [2223] Furthermore some of ion beams such as the deuteronbeam can be on their way to interact with the backgroundions [24 25] Therefore research in this area requires moredetailed calculations that will be covered in the future
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
References
[1] JD Lindl Inertial Confinement Fusion SpringerNewYorkNYUSA 1998
[2] J D Lindl P Amendt R L Berger et al ldquoThe physics basisfor ignition using indirect-drive targets on theNational IgnitionFacilityrdquo Physics of Plasmas vol 11 no 2 pp 339ndash491 2004
[3] S Atzeni and J Meyer-ter-VehnlThe Physics of Inertial FusionOxford University Press Oxford UK 2004
[4] L D Landau ldquoDie kinetische Gleichung fur den Fall Coulomb-scherWechselwirkungrdquo in Physikalische Zeitschrift der Sowjetu-nion vol 10 pp 154ndash164 1936
[5] L D Landau ldquoKinetic equation for the case of Coulomb inter-actionrdquo Zhurnal Eksperimentalrsquonoi i Teoreticheskoi Fiziki vol 7p 203 1958
[6] L Spitzer Jr Physics of Fully Ionized Gases Interscience NewYork NY USA 2nd edition 1992
[7] M W C Dharma-Wardana and F Perrot ldquoEnergy relaxationand the quasiequation of state of a dense two-temperature non-equilibrium plasmardquo Physical Review E vol 58 no 3 pp 3705ndash3718 1998
[8] D O Gericke M S Murillo and M Schlanges ldquoDense plasmatemperature equilibration in the binary collision approxima-tionrdquo Physical Review EmdashStatistical Nonlinear and Soft MatterPhysics vol 65 no 3 Article ID 036418 2002
[9] L S Brown D L Preston and R L Singleton Jr ldquoChargedparticlemotion in a highly ionized plasmardquo Physics Reports vol410 no 4 pp 237ndash333 2005
[10] J N Glosli F R Graziani RMMore et al ldquoMolecular dynam-ics simulations of temperature equilibration in dense hydrogenrdquoPhysical Review E vol 78 no 2 Article ID 025401(R) 2008
[11] G Dimonte and J Daligault ldquoMolecular-dynamics simulationsof electron-ion temperature relaxation in a classical Coulombplasmardquo Physical Review Letters vol 101 no 13 Article ID135001 2008
[12] B Jeon M Foster J Colgan et al ldquoEnergy relaxation rates indense hydrogen plasmasrdquo Physical Review EmdashStatistical Non-linear and Soft Matter Physics vol 78 no 3 Article ID 0364032008
[13] MMahdavi and T Koohrokhi ldquoNuclear elastic scattering effecton stopping power of charged particles in high-temperaturemediardquoModern Physics Letters A vol 26 no 21 pp 1561ndash15702011
[14] M Mahdavi and T Koohrokhi ldquoEnergy deposition of multi-MeV protons in compressed targets of fast-ignition inertial con-finement fusionrdquo Physical Review E Statistical Nonlinear andSoft Matter Physics vol 85 no 1 Article ID 016405 2012
[15] M Mahdavi T Koohrokhi and R Azadifar ldquoThe interactionof quasi-monoenergetic protons with pre-compressed inertialfusion fuelsrdquo Physics of Plasmas vol 19 no 8 Article ID 0827072012
[16] L S Brown andR L Singleton ldquoTemperature equilibration ratewith Fermi-Dirac statisticsrdquo Physical Review E vol 76 no 6Article ID 066404 2007
[17] R L Singleton ldquoCharged particle stopping power effects onignition some results from an exact calculationrdquo Physics of Plas-mas vol 15 no 5 Article ID 056302 2008
[18] D Kremp M Schlanges and W-D Kraeft Quantum Statisticsof Nonideal Plasma vol 25 of Atomic Optical and PlasmaPhysics Springer Berlin Germany 2005
[19] J C Fernandez B J Albright F N Beg et al ldquoFast ignition withlaser-driven proton and ion beamsrdquoNuclear Fusion vol 54 no5 Article ID 054006 2014
[20] M Tabak J Hammer M E Glinsky et al ldquoIgnition and highgain with ultrapowerful lasersrdquo Physics of Plasmas vol 1 no 5pp 1626ndash1634 1994
[21] M Roth T E Cowan M H Key et al ldquoFast ignition by intenselaser-accelerated proton beamsrdquoPhysical Review Letters vol 86no 3 pp 436ndash439 2001
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Advances in High Energy Physics 7
[22] BMHegelich B J Albright J Cobble et al ldquoLaser accelerationof quasi-monoenergetic MeV ion beamsrdquo Nature vol 439 no7075 pp 441ndash444 2006
[23] M Roth D Jung K Falk et al ldquoBright laser-driven neutronsource based on the relativistic transparency of solidsrdquo PhysicalReview Letters vol 110 no 4 Article ID 044802 2013
[24] D-X Liu W Hong L-Q Shan S-C Wu and Y-Q Gu ldquoFastignition by a laser-accelerated deuteron beamrdquo Plasma Physicsand Controlled Fusion vol 53 no 3 Article ID 035022 2011
[25] X Yang G H Miley K A Flippo and H Hora ldquoEnergyenhancement for deuteron beam fast ignition of a precom-pressed inertial confinement fusion targetrdquo Physics of Plasmasvol 18 no 3 Article ID 032703 2011
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
High Energy PhysicsAdvances in
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
FluidsJournal of
Atomic and Molecular Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in Condensed Matter Physics
OpticsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstronomyAdvances in
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Superconductivity
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Statistical MechanicsInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
GravityJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
AstrophysicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Physics Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Solid State PhysicsJournal of
Computational Methods in Physics
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Soft MatterJournal of
Hindawi Publishing Corporationhttpwwwhindawicom
AerodynamicsJournal of
Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
PhotonicsJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Biophysics
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
ThermodynamicsJournal of