Magnetic Confinement Fusion Energy

Research: Past, Present and Future.November 3, 2005.

Dr M. J. Hole, Department of Theoretical Physics, RSPSE

ZETA (UK), 1940 - 1950Zero Energy Toroidal Assembly

JET (EU), 1980 - Joint European Torus

ITER (Earth), 2015 –International Thermonuclear Experimental Reactor

Contents

(1) What is fusion energy?

(2) Magnetic confinement concepts

(3) Improvements in fusion plasma performance

(4) Advances in Australian theoretical plasma physics research

(5) The next step in fusion plasma physics

(6) Summary and Discussion

1.0 What is fusion ?

(1) D2 + T3 He4 + n1 + 17.6 MeV

Thermonuclear fusion :

Coal combustion (anthracite, dry mass) (4) C6H2 + 6.5 O2

6 CO2 + H 20 + 30 eV

By comparison… simple to initiate, very low yield

energy gain ~ 450:1

Nuclear fission : normally(3) U235 + n Xe134 + Sr100 + n + 200 MeV+ soup of long-lived radionuclides, Sr90, Cs137

• Advanced fission cycles can reduce long-lived waste

1.1 Conditions for fusion power

• Achieve sufficiently high

ion temperature Ti

exceed Coulomb barrier

density nD energy yield

energy confinement time E

nD ETi>3 1021 m-3 keV s

• “Lawson” ignition criteria : Fusion power > heat loss

Fusion triple product

• At these extreme conditions matter exists in the plasma state

100 million °C

1.2 The plasma state : the fourth state of matter

• plasma is an ionized gas • 99.9% of the visible universe is in a plasma state

Inner region of the M100 Galaxy in the

Virgo Cluster, imaged with the Hubble

Space Telescope Planetary Camera at

full resolution. A Galaxy of Fusion Reactors.

• Fusion is the process that powers the sun and the stars

2.0 Routes to Fusion Power : Hot Fusion

Laser confinement : (uncontrolled fusion)• Focusing multiple laser light beams to a target• Principally funded (US,France, UK) to continue nuclear

weapons research following comprehensive test ban treaty.

… concept designs for power plants do exist.

Magnetic confinement:

(controlled fusion)use of magnetic fields to confine a plasma : eg. tokamak

Demonstrated Q = power out/power

~0.7

2.1 Hot Fusion Power Plant designs

Final Report of the European Fusion Power Plant Conceptual Design Study, April 13, 2005

Q = Pout /Pin ~1

3.0 Progress in magnetically confined fusion

• “Breakeven” regime :

Eg. Joint European Tokamak : 1983 -

• “Ignition” regime, Q∞ : Power Plant.

D2 + T3 He4 (3.5 MeV) + n1 (14.1 MeV)

• “Burning” regime :

≥ PinQ>5 ITERPout

1997 : Q=0.7, 16.1MW fusion 1997- : steady-state, adv.

confinement geometries

3.1 Progress comparison to # CPU transistors per unit area

Fusion progress exceeds Moore’s law scaling

4.0 Some advances in Australian Theoretical Plasma Physics

• Understanding magnetic perturbations• Advances in plasma modelling• Observation-lead theory development• Exploring the dynamics of turbulence• Frustrated Taylor relaxation• Burning Plasma Physics

BushfiresEnergetic Particle Mode physics

4.1 Understanding Magnetic Perturbations : Blending diagnostics, interpretation and theory.

M. J. Hole, L. C. Appel, R. Martin

|n|=1 chirping

|n|=2

|n|=1

Mirnov Coil Modelling and Design

pafp

f HHHV

V

• Diagnostic Transfer Function:

Va

Vf

p

op V

VH

o

aa V

VH

a

ff V

VH

MV coil/ transmission line

amplifier

A/D converter

Graphite shield

dt

dBNAV c

p

+-

Vo +-

plasma

+-

+-

Graphite coated centre-column

• Stray Capacitance modelling M. J. Hole & L. C. Appel accepted IEE Proc. Ccts. Dev. Sys.

•System resonance, remote calibration

L. C. Appel, & M. J. Hole, Rev. Sci. Instrumen ts, 76(9)., Sep, 2005

Magnetic Eigenmode DetectionM. J. Hole, L. C. Appel, R. Martin

• A new approach to an old problem: poloidal (m) and toroidal (n) mode number identification in magnetic confinement

3

2 1

4

3

2 1

4

Motivation : Characterise magnetic perturbations, which can lead todeterioration in confinementdisruption

Limitations of Standard Techniques

(A) Phase counting of time series data

(B) As above, but mapped to straight field line coordinates

Observed poloidal mode structure on centre column magnetic array for MAST shot 2952 R. J. Buttery et al., Contr. Fus. Plas. Phys. 25A pp. 597, (2001)

Large aspect ratio approximations often used for mapping

(C) Singular Value Decomposition in time-series data :

)1(...)1(

)()(

)0(...)0(

1

1

1

1

sMs

sMs

M

tNxtNx

txtx

xx

NX

channels

time

Limitations : Data taken at different times, not all coils used at onceTVSUX

Polar plot of the first 2 SVD principal axes vs. *. Nardone C., Plasm. Phys. Con. Fus., 34 (9), 1992.

JET #23324

Limitations : Cannot resolve modes degenerate in n,m &/or .

Fourier - SVD analysis resolves eigen-modes

• Solve for a and {n1,n2,…,nm} s.t. is minimized for all modes with ni nc, and nc =Nyquist mode number.

αγF r

M

nc2

Mjnjn

jnjn

jnjn

N

...α

e...e

......

e...e

e...e

γ

F

...

F

F

MMN

M

M

12

1

1

221

111

~~,,F

~~F αγ• For all coils:

3

2 1

4

• For each coil, spectrogram gives complex Fourier transform :

a1,..., aM = mode complex amplitudes n1,…,nM = mode numbers

N

n

tjnnk

negx1

)(F

Statistical Analysis can quantify fit

3

2 1

4

e.g. for M=1,

• Quantify r by comparing to significance levels generated by forming the pdf of noise.

Fk

F

Fn

Re

Im

k

kn

FF

FF

,

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

F=

0.01

F=

0.05

F=

0.1

F=

0.5

Cumulative Distribution Function for M=1

F(r

)r

F

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

r

P(r)

P(r) for M=1, F=1

P(x

r

)=0.

1

P(x

r

)=0.

5

M. J. Hole and L. C. Appel, Europhysics Conf. Abstract, 27A, P3.132. 30th EPS Conf. On Controlled Fusion and Plasma Physics. St Petersburg , Russia,2003.

20 40 60 80 100f [kHz]

0

0.2

0.4

2

4

020 40 60 80 100

Mode identification with statistics

shot #4636 : a beam-heated deuterium discharge

t=100 ms

10% level (one mode)

t [ms]

log 10

|B

[T]|

40 60 80 100 120 140

100

200

300

400

f [k

Hz]

4836 -6

-7

-8

-9

-10

-11

-12

220

t=48.75 ms

40 80 120 180

f [kHz]

0

0.2

0.4

|| (

1

0-7)

2

4

6

040 80 120 180 220

|| (

1

0-6)

F

rF

r

Is there an optimum coil placement ?

Aim: Find s.t. is maximised as 0.

θ~ ),(),...,,(minmin css nnrnrr 1

NN nnj

nnj

nnj

nj

nj

nj

e

...

e

e

e

...

e

e

f

2

1

2

1

,F

New expression for rs(n) :

mode number error

2/1

112

11

N

i

njN

i

njs

ii eeN

nr

plasma signal basis function

Can these positions be generated by an algebraic mapping?

0θ~

1

9θ~

2

60θ~

3

0 0.1 0.2 0.3 0.40

40

80

120

160

200

(

)

0.5

Method: Monte-Carlo sample(i) generate random arrangements for (ii) Find rmin for each

θ~

θ~

e.g. N=3, nc=40

0~

11 θ

24

~θ

33

~θ

42

~θ

e.g.• is not unique. Choose mapping toθ

~θ

remove reflections and rotations

Optimum locations related to density of rational numbers ?

4.2 Plasma Modelling : Equilibrium and Stability

Mega-Ampere Spherical Tokamak

M. J. Hole and the MAST Team

Baseline Achieved (2002)Major Radius 0.85 m 0.85 mMinor Radius 0.65 m 0.65 mElongation 2.5 2.4Triangularity 0.5 0.5Plasma Current 2 MA 1.2 MAToroidal Field 0.51 T 0.51 TNBI Heating 5 MW 2.7 MW RF Heating 1.5 MW 0.8 MWPulse Length 5 sec 0.5 sec

Plasmas are physics-rich

Ruby TS time(m,n) = (2,1) mode

#7085

Inferring the magnetic topology : enabled by precision diagnostics …

• ~300 point TS ne, Te

• Zeff ni = 0.78 ne

• CXR Ti = 1.1 Te

e

i

e

ie T

T

n

npp 1

Pressure fit:

#7085 @ 290ms

… interpretation & ideal-MHD force-balance

• Boundary taken from EFIT

• Pressure from kinetic fit

• Ill = <J.B>/<B.> taken from EFIT: inconsistent with computed BS fraction

Kinetic reconstruction of #7085

M. J. Hole, PPCF

Ideal MHD stabilityLinearized ideal MHD eigen-value equations for a plasma displacement can be written :

02

~

*

~~

*

~,, ξξKξξW

)(

~

ntieξ

2<0 secular growth unstable low n external modes form hard performance limits.

Potential energy Kinetic energy

Z(m)

1

-11R(m)

n=1Proximity to instability determined by

increasing pressure gradient, until plasma unstable.

MAST equilibriumstable equilibriumunstable equilibrium

● Grayscaled data is a histogram of MAST operating space

Probing performance limits reveal new physics regimes

Conventional scaling limits :

n il4

Trajectories to disruption

M. J. Hole et al, Plasma Physics and Controlled Fusion, 47(4), 2005.

• Multiple energetic components, resolved by different diagnostics

[1] R. Akers et al. Plas. Phys. Con. Fus. 45, A174-A204, 2003

• Typical energy schematic breakdown [1]

• Rotational energy ~ 2% of WMHD, v /vth <0.7.

Pressing the limits of ideal MHD

4.3 Theory Development : Multiple Fluid ModelsG. Dennis and M. J. Hole

• Modern fusion plasmas are not thermalized, but are energy pumped in a steady-state

• Multiple energetic reservoirs• Energetic components have different rotation profiles

Single thermalized, stationary fluid no longer sufficient

Multi-fluid force balance - a first attemptConsider multiple quasi-neutral fluids, such that :• fluids have independent temperature, and arbitrary flow• pressure for each species is isotropic, p= p||

• inter-specie collisions may be neglected• velocity distribution function for each specie is Maxwellian• Plasma has toroidal symmetry

v v E v Bi i i i i i i ip Z n Z n

General idea : Reduce multiple single-fluid force balance

Into two algebraic equations (Bernoulli + toroidal comp.) , and a generalized Grad-Shafranov (force – balance) equation

Solve numerically, by modifying a single fluid code that handles rotation, FLOW [1]

[1] L. Guazzotto, R. Betti, J. Manickam, S. Kaye, PoP 11, 604, 2004

Application to MAST-like discharge

R [m]

n i [1

020 m

-3]

R [m]

v pol

oida

l [km

s-1]

R [m] R [m]

v [k

m s

-1]

p [k

Pa]

thermal

fast-ion

• Fast-ion ni core localized, rapid poloidal & toroidal rotation• improved resolution of fast-ion & thermal species in force balance

R [m]

Z [

m]

R [m]Z

[m

]

fas

t-io

n t

herm

al

• Turbulence is present at scales from coffee cup to universe.• Characterized by unpredictability, strong mixing effect, etc.• Research Aim : infer universality from complete complexity.

[NASA web site 　 http://solarsystem.nasa.gov]

4.4 Turbulence : fundamental in nature R. Numata, R. L. Dewar, and R. Ball

In 2D, large-scale, spontaneously-generated, coherent structures often observed.

• Zonal flow creation and transport suppresion due to the zonal flow is a key physics for plasma confinement.

[Z. Lin et al, Science (1998)]

Zonal flows improves plasma confinement

Example : Zonal flow in a tokamak plasma

Destruction of electrostatic elongated radial fluctuations by zonal flow transport suppression

• Zonal flow also observed in other systems (e.g. geophysical fluids), with analogous forces (eg. Coriolis force)

Drift-wave turbulence simulations suggest “universality” : power law spectrum

Dynamics described by fluid equations of motion

ny

nnt

n

nt

2

422

)(},{

)(},{

toroidal resistivity Density profile scale length

viscosity

diffusion term

If = drift wavesIf ~ 1

• Small scale fluctuation grows linearly by drift wave instability (k ~ 1).

• Large fluctuation amplitudes evolve nonlinearly, and may saturate

• Observe an inertial range where energy spectrum obeys power law.

linear growth

saturation

Time(c)

Ene

rgy

inertial range

energy input

Ene

rgy

k

eg: n, density perturbations

… and explored by numerical simulations

Turbulence suppression at low power input

• Dynamical systems model for :thermal energy W, kinetic energy of turbulence N, andshear flow v kinetic energy

• Constant, but arbitrary power input Q• Equilibria surface plots reveal striking

dynamics with increasing power input

R. Ball, Phys. Plas., 12, 090904-5, 2005

Motivation : Explore dynamics of turbulence with power input, and suggest experiment optimization

R. Numata, R. Ball and R. L. Dewar

Shear flow can grow as power input is withdrawn

zonal flow ?

4.5 3D Magnetic ConfinementM. J. Hole, S. R. Hudson, R. L. Dewar

Do 3D ideal MHD equilibria with p0 exist ?

+ BC’s, eg.,0,, 0 BJBBJ p 0nB

Ideal MHD model

• General Case : ,/ 2BpJ B B||J

0 J JB

Singular nature of B. . J =0 p=0 at rational (or q)

JB 1With solution and constant on a field line

• If a symmetry exists magnetic field forms flux surfacesEg. toroidal symmetry :

In 3D, regions of rational (or q) do not collapse to form flux surfaces.

In regions of rational , p=0.

S. Kumar, PRL, PhD stduent

But some flux surfaces survive…Kolmogorov Arnold Moser (KAM) Theory : outlined by Kolmogorov (1954), proved by Arnold (1960) and Moser (1962)

• Perturb Hamiltonian by some periodic functional H1,

• Moser considered integrable Hamiltonian H0 with a torus T0, and a set of frequencies with .m 0 , with m an integer array.

and stepped pressure equilibria can exist

(Existence of 3-D Toroidal MHD Equilibria with Nonconstant Pressure Comm. Pure Appl. Maths, XLIX, 717-764).

• In 1996, Bruno and Laurence derived existence theorems for sharp boundary solutions for tori for small departure from axisymmetry.

• KAM theory states: if tori are sufficiently far from resonance (ie. satisfy a Diophantine condition), some tori survive for < c

If sufficiently irrational, some flux (KAM) surfaces survive

Stepped Pressure Profile Model

Generalization of single interface model :- Spies et al Relaxed Plasma-Vacuum Systems, Phys. Plas. 8(8). 2001- Spies. Relaxed Plasma-Vacuum Systems with pressure, Phys. Plas. 8(8). 2003

iR

iii d

PBU 3

0

2

12

Cl iC iV iii

s

dH AdlAdlBA ..)( 3

iR ii dPM 3/1

potential energy functional:

helicity functional:

mass functional: loop integrals conserved

System comprises: • N plasma regions Pi in relaxed states.• Regions separated by ideal MHD barrier Ii.• Enclosed by a vacuum V,• Encased in a perfectly conducting wall W

…I1

In-1

In

V Pn

P1

W

1st variation Taylor “relaxed” equilibria

Energy Functional W:

N

iiiiii MHUW

1

2/ Setting W=0 yields:

0:

0

0:

0)2/(

0:

constant

:

02

nB

B

B

nB

BB

W

V

BP

I

P

P

i

i

i

ii

n = unit normal to interfaces I, wall W

ii xxx 1

Poloidal flux pol, toroidal flux t constant during relaxation:

constant constant,:

constant:

polV

tV

tPi

V

Pi

Tokamak like relaxed equilibria can exist

Eg. 5 layer equilibrium solution

Contours of poloidal flux p

• q profile smooth in plasma regions, • core must have some reverse shear• Not optimized

Work in progress: • 2nd variation stable equilibria• Application to transport barrier modeling

M. J. Hole, S. R. Hudson and R. L. Dewar, INCSP and APPTC, Nara, August 2005

● Strategy

– Look at integrable and near-integrable cases to provide baseline for fully 3D cases

4.6 Spectrum of 3-D ideal MHD

● Problems unique to 3D

– Wave equation non-separable

– Statistical characterization sensitive to spectral truncation method (“regularization”)

R. L. Dewar and B. McMillan

Eg. W-7X

Eigenvalue equation for interchange modes in cylindrical (integrable) geometry

)/( 0)()(),( Rinzimtr errrt r

• equations of motion eigenmode equation for stream function

• Like quantum, microwave & acoustics spectral problems, ideal MHD on static equilibrium is Hermitian real eigenvalues (= 2

— unstable modes have 2 < 0, = i).

t2 F

MHD fluid displacement

linearized + averaged over helical ripple

Computing the interchange spectrum

0

=2>0

Alfvén continuum

=2<0

discrete modesaccumulation points

• interchange instabilities occur at resonant n,m. ie. n m 0

• Qualitatively, spectra looks like

• The most unstable modes have no radial nodes (l=0) in the plasma

• Details of spectrum determined by : the rotational transform, iota the pressure profile

0 22r

p r p r r( ) 05 61 6 5

Examples :

m, n space for most unstable l=0 modes

(0)

(1)-

-

At large m, eigenvalue depends only on slope, infinite degeneracy at each rational unless we truncate spectrum

n/m

Statistics of nearest neighbour eigenvalues describes “universality” class of system

• Suppose P(s)ds = probability of finding two consecutive eigenvalues n a distance s apart:

• Shape of P(s) describes properties (eg. integrability) of system,

Generic chaotic systems give pdf like random matrices from a Gaussian Orthogonal Ensemble

Level repulsion

Generic integrable systems give Poisson distribution, as if random! (Eigenvalues uncorrelated)

No avoidance of degeneracies

TAE gap

EAE gap

n

/

A

0 0.2 0.4 0.6 0.8 1.0

0.5

1.0

1.5

2.0

2.5

0.0

Eg. Alfven eigenmode gaps in continuum of shear Alfven eigenmodes of a tokamak pklasma

NAE gap

Statistics of interchange modes reveal possible new universality class!

Separable system, but pdf is non-Poissonian —

Is this a new universality class?

Data set consists of >32,000 of the most unstable eigenvalues: l = 0, m < mmax

• Ignore O(1/m) and higher terms [equivalent to Suydam condition], and apply abrupt truncation at mmax

Approaches a delta function as m

non-Poissonian statistics persist with finite m corrections

4.7 Burning Plasma Physics A. Sullivan, R. Ball, R. L. Dewar, M. J. Hole

/

A

n0 0.2 0.4 0.6 0.8 1.0

0.5

1.0

1.5

2.0

2.5

0.0

Modelling the dynamics of a bushfire

Aim : develop a dynamical systems model of bushfire behaviour that is better than real-time for operational use.

no physicsfast (4hrs in 1min.)

detailed physicsslow (1 min. in 2 days)

• empirical response models, limited in scope.

• detailed chemistry and physics of combustion and heat transfer

quasi-physical

A. Sullivan, R. Ball, J. Gould, I. Enting

physical empirical

• simplified processes• no chemistry

Modus Operandi : Benchmarked to reality!• Key ingredients : fuel, topography, atmosphere, fire.

• Graph and network theory abstract description of fire behaviour.

• Datasets : grassland experiments conducted in mid-1980s will be used as basis of model development and testing.

Fusion : the rise of Energetic Particles Modes

cos/10 RrBB • leads to coupling among poloidal harmonics.

m

mm nmtitr exp,,,

mmikb ||

• Fourier decompose electrostatic potential in poloidal harmonics

)(

1)(|| rq

mn

Rrk m RBrBrq /with &

• Toroidicity induced gaps in the Alfvén continuum appear

AmAm vrkvrk )()( 1||||

Eg. : Alfvén gap modes (in fusion, discovered by R. L. Dewar)

0222 Av/.b.b

with 0 ||bbE Ai and 0BB/b

• For TAE’s, reduced ideal MHD equation for high-mode number shear Alfvén waves

M. J. Hole, L. C. Appel, S. Sharapov

Continuum frequencies of Alfvén eigen-modes

r

• TAE’s

•Example of numerically computed continuum of eigen-modesm

=2

m=2

m=

3

m=3

m=3

m=3

/

A

TAE gap

EAE gap

n

/

A

0 0.2 0.4 0.6 0.8 1.0

0.5

1.0

1.5

2.0

2.5

0.0

D+ driven Alfvén eigenmode activity•MAST discharge 5586 exhibits multiple mode frequency activity

– Ip=600kA, Btor = 0.4 T, =1.9, =a/R=0.7– 0.8 MW co-injected 34keV D, v||/vA = 0.5 (Zeff=3.9)

Drive calculations require knowledge of ion distribution function

[1] K. McClements et. al. PPCF, 41, pp661, 1999),,(),,,( 00 PEfvZRf

TAE Drive: Analytic Calculations• Wave-particle drive analysis for (m,n)=(4,3) modes

r [m]

0 0.4 0.8 1.2

b(v||=vA/3, =0) 74mm

m 14mm

l

p

m

AlbAlb

z

pl

vvvv

r

P

P

fdC

l

lmP

1

0||0||

,

0)(

3

,,

21

• Power drive from particles to wave P , collapses to 1D integral over

, and =constant describes the unperturbed orbit,l = poloidal mode number describing variation of along orbit,l=1/(1-2l), Cl

(p) = constants describing TAE eigenfunction,

vA0 = Alfvén velocity at magnetic axis (~2.9 x 106 ms-1)

cosbrr rp=1; b>> m

p=2; m>> b

b

rr

(1) large aspect ratio , equilibrium scale lengths » mode scale length m

(2) circular flux surfaces and drift orbits (3) narrow orbit k

-1>b

(4) radially localised mode, k-1>m,

(5) ignore FLR effects, b>L

(6) neglect continuum damping(7) neglect energy gradients in f0

v||=vA/5

v||=-vA/5

v||=vA/3

v||=-vA/3

Counter-passing particles

Co-passing particles

Calculation of f0/ P

• Distribution functions obtained from LOCUST : a gyro-orbit NBI fast particle simulation code f0(R,Z,v, =v||/v)

• projections of resonant particle distribution onto , P plane

P /P0

[ k

eV/T

]

P /P0

P /P0

P /P0

[ k

eV/T

]

[ k

eV/T

]

[k

eV/T

]

Significant Wave drive, although beam sub-Alfvénic

Analytic v|| / (%)

b<<m b>>m

-vA/5 0.2 0 -vA/3 1.0 1.5 -vA 0 0 vA 0 0 vA/3 9.9 9.2 vA/5 0.7 0

Counter-passing

Co-passing

• Integrate over to obtain TAE drive

Significant TAE wave drive, even though Avv ||

5.0 What is the future of fusion energy?

ITER is an international collaboration to build the first fusion science experiment capable of producing a self-sustaining fusion reaction, called a “burning plasma.”

It is the next essential and critical step on the path toward demonstrating the scientific and technological feasibility of fusion energy.

US. Department of Energy, Office of Sciences

DOE Office of Science Strategic Plan February, 2004“The President has made achieving commercial fusion power the

highest long-term energy priority for our Nation.”

5.1 The future is ITER

Plasma conditions

15MAIp, plasma current

6.2m, 2.0mMajor,minor radius

10Q = fusion power/ aux.heating

500MWTotal Fusion power

80106 °C<Ti>

73MWAuxillary heating, current drive

837 m3Plasma Volume

5.3TToroidal field @6.2m

5.2 ITER ObjectivesProgrammatic● Demonstrate feasibility of fusion energy for peaceful purposes

Physics● Produce and study a plasma dominated by particle (self) heating● Steady-state power gain of Q = 5, higher Q for shorter time● “Grand Challenge” burning plasma science :

plasma self-organization, non-Maxwellian and nonlinear physics, confinement transitions,

exhaust and fuelling control, high “bootstrap” (self-current driven) regimes, energetic

particle modes, plasma stability.

Technology● Demonstrate integrated operation en-route to a power plant● Investigate crucial materials issue:

First wall neutron flux loading > 0.5 MW/m2

Average fluence > 0.3 MW years/m2 ● Test tritium breeding blanket for a demonstration reactor (DEMO)

The first wall of a fusion reactor has to cope with the ‘environment from hell’ so it needs a “heaven sent surface”.

5.3 ITER Scaling – Why so big?A. Power Balance LH PPP

M=nD(0) ETi (0) >3 1021 m-3 keV s• Ignition criteria : P > PL

Auxiliary heating heating power loss

• D-T collision cross section <v> peaks at Ti(0) ~100 million K

(1)

B. Energy Confinement Time : empirical scaling

RaMRPnBIHf mHTMAHE /,,,,,,,,

Confinement mode H-mode: HH~1

Plasma current

magnetic field

major radius elongation = b/a

aspect ratio

(2)

C. Density Limit : ~ empirical 2MA)/( aIn

(4)

(3)

Subs. (2), (3) and Ti- into (1)

Finite Q : H I R a Q QH MA / //

50 51 3

H I R aH MA / / 50 1For Q=:

(5)

F. Materials Limits : T10cB• Superconducting NbTi or NbSn

OH coil TF coil shield plasma

Radial Tokamak build

shield TF coilRcoil BS

a

R

• Divertor ablation limits during ELM’s, disruption• Minimize neutron flux loading

5.3 Design determined by physics, technology

3/,3.2 aRfE. Engineering Choices :

D. Edge magnetic winding (or “safety”) factor

R

a

I

faBq

MA

T595

• f = plasma geometric shaping factor• plasma unstable for q95< 2.5 q95~ 3

Fold A – F + design objective Q>5

~ITER

Fusion Power Pf ~ 500 MW

nDT 1020 m-3

Rc, BS, a, R 3.2, 1.0, 2.0, 6.2

Ip, plasma current 15 MA

5.4 Who is ITER?• ITER is a consortium of 6 nations and alliances under the auspices

of the IAEA

5.5 ITER technology has been demonstrated

5.7 ITER site selection

June 28, 2005

5.8 Fusion energy time-scales

Source: Accelerated development of fusion power. I. Cook et al. 2005

Australian Government Energy White paper (2004)....

2005 20502020

materials testing facility

ITER

today’s experiments

demonstration power-plant

commercial power-plants

5.9 Towards a Unified Australian Fusion Science Program

• Collection of scientists and engineers from multiple research disciplines supporting a mission orientated goal :

controlled fusion as an energy source

• ITER distribution email list ~100 scientists and engineers

• Attendees at ITER Forum meetings ~ 30 scientists.

• Activities to dateIntegration : collation of fusion energy capabilities, ITER workshop proponent.Presentations: DEST, DITR, DEH, AIE, ANSTO, EU commission

representatives, members of parliamentSubmissions : parliamentary enquiry on non-fossil fuels, NCRISMedia : Various newspapers, ABC radio… Australasian Science

Australian ITERForum

The University of SydneyAUSTRALIA

FLINDERS UNIVERSITYADELAIDE AUSTRALIA

THE AUSTRALIAN NATIONAL UNIVERSITY

UNIVERSITY OF CANBERRA

Australian Nuclear Science &Tec. Org.

Australian Ins. of Nuclear Science & Eng.

• H-1 National Facility• Theory program• High beta physics

• Quasi-toroidal pulsed cathodic arc

• Plasma theory/ diagnostics

• plasma fuelling, • soft x-ray imaging

• Computational MHD modelling

• High heat flux alloys• MAX alloys are one promising route

• Manages OPAL research reactor• ~1000 staff

• Consortium of all Australasian nuclear research institutes

Australian ITERForum

5.10 Next Step Challenges for Fusion Theory

(1) Burning Plasma science : Fusion plasmas are not thermalized, but are energy pumped

in a steady-state Produces new challenges to description of steady-state, and

magnetic field Multiple energetic resorvoirs can drive different mode

activity, which may degrade confinement Burning plasmas are high beta environments,

(2) Improved understanding of 3D magnetic confinement: stellarators tokamaks, through error fields (which can lead to disruption)

(3) Continued advance in understanding turbulence, dynamics, and effect on confinement

6.0 Conclusions

(1) Described magnetic confinement fusion, and progress to date

(2) Provided an overview of some ANU plasma and fluid theory research, motivation, and international linkages: focus on

Understanding magnetic perturbations Advances in plasma modelling Observation-lead theory development Exploring the dynamics of turbulence Frustrated Taylor relaxation Burning Plasma Physics

(3) Introduced the next step for fusion science: ITER

(4) Highlighted some theoretical challenges for the future.

Very Cool Kermit!