FIRE Physics Basis

C. Kessel for the FIRE TeamPrinceton Plasma Physics Laboratory

FIRE Physics Validation ReviewMarch 30-31, 2004Germantown, MD

AES, ANL, Boeing, Columbia U., CTD, GA, GIT, LLNL, INEEL, MIT, ORNL, PPPL, SNL, SRS, UCLA, UCSD, UIIC, UWisc

FIRE Collaboration http://fire.pppl.gov

FIRE DescriptionH-modeIP = 7.7 MABT = 10 TN = 1.80 = 2.4%P = 0.85 = 0.075%q(0) < 1.0q95 ≈ 3.1li(1,3) = 0.85,0.66Te,i(0) = 15 keVTe,i = 6.7 keVn20(0) = 5.3n(0)/n = 1.15p(0)/p = 2.4n/nGr = 0.72Zeff = 1.4fbs = 0.2Q = 12burn = 20 s

R = 2.14 m, a = 0.595 m, x = 2.0, x = 0.7, Pfus = 150 MWAT-ModeIP = 4.5 MABT = 6.5 TN = 4.2 = 4.7%P = 2.35 = 0.21%q(0) ≈ 4.0q95, qmin ≈ 4.0,2.7li(1,3) = 0.52,0.45Te,i(0) = 15 keVTe,i = 6.8 keVn20(0) = 4.4n(0)/n = 1.4p(0)/p = 2.5n/nGr = 0.85Zeff = 2.2fbs = 0.78Q = 5 burn = 32 s

portplasma

divertorbaffle

passiveplate

VV

FIRE Magnet Layout

TF Coil

CS1

CS2

CS3

PF1,2,3PF4

PF5

Error field correction coils

Fast vertical and radial position control coil RWM feedback coil

Fe shims

FIRE Magnets

CS1

CS2CS3

PF1,2,3 PF4

PF5

TF CoilsLimit flattop

20 s at BT = 10 T (H-mode)48 s at BT = 6.5 T (AT-mode)

TF ripple (max) = 0.3%0.3% loss H-mode8% loss AT-mode (Fe shims)

PF CoilsProvide H-mode operation

0.55 ≤ li(3) ≤ 0.85 (SOB,EOB)0.85 ≤ li(3) ≤ 1.15 (SOH,EOH)ref-5 ≤ (Wb) ≤ ref+51.5 ≤ N ≤ 3.0ramp = 40 V-s, flat = 3 V-s

Provide AT-mode operation0.35 ≤ li(3) ≤ 0.65 (SOB & EOB)2.5 ≤ N ≤ 5.07.5 ≤ flattop(Wb) ≤ 17.5Ip ≤ 5.0 MAramp = 20 V-s

FIRE MagnetsVertical stabilityCu passive plates, 2.5 cm thick

For most unstable plasmas (full elongation and low pressure), over the range 0.7 < li(3) < 1.1, the stability factor is 1.3 < fs < 1.13 and growth time is 43 < g(ms) < 19

Internal Control CoilsFast vertical position controlFast radial position control (antenna)Startup assist

Error Correction CoilsStatic to slow response

Correct PF and TF coil, lead,etc. misalignments

ITER Error Coils

FIRE Magnets

Current strap, grounded at each end

Faraday shield(one side only)

Port flange

ICRF Port Plug

RWM Coil

Resistive Wall Mode Coils

DIII-DModes are detectable at the level of 1GC-coils produce about 50 times this fieldThe necessary frequency depends on the wall time for the n=1 mode (which is 5 ms in DIII-D) and they have wall ≈ 3

FIREFIRE has approximately 3-4 times the plasma current, so we might be able to measure down to 3-4 GIf we try to guarantee at least 20 times this value from the feedback coils, we must produce 60-80 G at the plasmaThese fields require approximately I = f(d,Z,)Br/o = 5-6.5 kAAssume we also require wall ≈ 3Required voltage would go as V ≈ 3o(2d+2Z)NI/wall ≈ 0.25 V/turn

FIRE Heating and CD

.32

.71

2.56

.65

FIRE Antenna Plan

4/24/01

Dimensions in m

1999 version of Vacuum vessel

1250

160 300Current straps

Faraday shield

Coax feeds

First wall Ant front-side 7/30/03

Adjustablecapacitorstructure

Shielding

Port outline

Each block =8 waveguides+ cooling

1250

720

Array of 768 waveguides in midplane port

536

EC Launcher

EC Launcher

Blow-up of one square

60

67

=ce=170 GHz

pe=ce

ICRF (20+ MW, 70-115 MHz)Ion heating @ 10 THe3 minority and 2T at 100 MHz

Ion heating @ 6.5 TH minority and 2D at 100 MHz

Electron heating/CD @ 6.5 T70-75 MHz, 20 = 0.14-0.21 A/W-m2

LHCD (30MW, 5 GHz)n|| ≈ 1.8-2.5, n|| = 0.3

NTM control @ 10 T

Bulk CD/NTM @ 6.5 T20 = 0.16 A/W-m2

ECCD (??MW, 170 GHz)LFS, O-mode, fundamental

NTM control @ 6.5 T20 = 0.004 A/W-m2 (at 149 GHz)

ICRF Heating and CD

Module A

Module B

.27

.23

10 8 6 4 2 0 2 4 6 8 10

1

2

3

nz

Launched

spectrum

"Good CD"

region

.32

.71

2.56

.65

FIRE Antenna Plan

4/24/01

Dimensions in m

1999 version of Vacuum vessel

Want to reduce power required to drive on-axis current

2 strap antenna and port geometry provides only 40% of ICRF power in good CD part of the spectrum

4 strap antenna can provide 60% of power in good CD part of spectrum

Expanding antenna cross-section and going to 4 straps reaches 80% in good CD part of spectrum

Power HandlingFirst wallSurface heat flux

Plasma radiation, Qmax = P+ Paux

Volumetric heatingNuclear heating, qmax = qpeak(Z=0)

VV, Cladding, Tiles, Magnets….Volumetric heating

Nuclear heating, qmax = qpeak(Z=0)

DivertorSurface heat flux

Particle heat flux, Qmax = PSOL/Adiv(part)Radiation heat flux, Qmax = PSOL/Adiv(rad)

Volumetric heatingNuclear heating, qmax = qpeak(divertor)

plasma

VV Clad Tile

Power HandlingPulse length limitations

VV nuclear heating (stress limit), 4875 MW-s -----> Pfus (qVV

nuclear)

FW Be coating temperature, 600oC -----> QFW & Pfus (qBe

nuclear)

TF coil heating, 373oK -----> BT & Pfus (qCu

nuclear)

PF Coil heating-AT-mode, 373oK -----> Ip, li, p, and (not limiting)

Component limitations

Particle power to outboard divertor < 28 MW

Radiated power on (inner&outer) divertor/baffle < 6-8 MW/m2

Power Handling/Operating SpaceFIRE H-mode Operating Space

N limited by NTM or ideal MHD with NTM suppression-----> maximum Pfus

Higher radiated power in the divertor allows more operating space, mainly at higher N

-----> maximum Pfus

Majority of operating space limited by TF coil flattop-----> flattop ≤ 20 s

High Q (≈15-30) operation obtained with

Low impurity content (1-2% Be)Highest H98 (1.03-1.1)Highest n/nGr (0.7-1.0)Highest n(0)/n (1.25)

H98(y,2) ≤ 1.1

Power Handling/Operating SpaceFIRE AT-mode Operating Space

N is limited by ideal MHD w/wo RWM feedback -----> maximum Pfus

Higher radiated power in the divertor allows more operating space, mainly at higher N

-----> maximum Pfus

Majority of operating space limited by VV nuclear heating-----> flattop ≤ 20-50 s

Design solutions to improve VV nuclear heating limit, could reach PF coil limit, function of Ip

Number of current diffusion times accessible is reduced as N, BT, Q increase

H98(y,2) ≤ 2.0

FIRE Particle Handling

VHFS = 125 m/sParks, 2003

Cryopumping in slanted portsMidplane pumping for pumpdown & bakeout

HFS (vmax = 125 m/s, determined by ORNL), LFS, VL

Parks HFS modeling, deposition to axis

WHIST analysis indicates n(0)/n ≤ 1.25

MHD StabilityH-modeSawtooth ---> unstable, weak impact on burn, coupling to global modes?

NTM’s ---> unstable or stable?, LHCD ’ stabilization, reduce N if near threshold, experiments with little or no NTM impact (DIII-D, JET, ASDEX-U)

Ideal MHD ---> over range of profiles N (n=1 or ∞) ≈ 3

AT-modeNTM’s ---> unstable or stable? q() > 2 everywhere, r/a(qmin) ≈ 0.8, ECCD/OKCD, LHCD multiple spectra

Ideal MHD ---> no wall/feedback, N (n=1) ≈ 2.5-2.8

---> with wall/feedback, VALEN analysis indicates 80-90% of with- wall N-limit (5-6), however, n=2,3 have lower N-limits?

Other MHD issuesBallooning/peeling modes, unstable with H-mode edge

Alfven and energetic particle modes, H-mode stable (unless higher N), AT not analized

No external rotation source

FIRE MHD StabilityNeoclassical Tearing Modes H-mode

Threshold for NTM’s is uncertain

Sawteeth and ELM’s are expected to be present and can drive NTM’s

Typical operating point is at low N and P

Can lower N further if near threshold

Lower Hybrid CD at the rational surfacesCompass-D demonstrated LH stabilizationAnalysis by Pletzer and Perkins showed stabilization was feasible (PEST3)Lowers Q(=Pfus/Paux)

EC methods require high frequencies at FIRE field and densities ----> 280 GHz

DIII-D (Luce) N ≤ 3, NTM weak impactASDEX-U, JET (Gunter) frequently interrupted NTM

confinement degradation

JET

(3,2) surface

12.5 MW

0.65 MA

n/nGr = 0.4

Q = 6.8

TSC-LSC

normal

FIR-NTM

Weak NTM, FIR-NTM

MHD StabilityRWM Stabilization AT-mode

RWM stabilization with feedback coils, VALEN analysis indicates 80-90% of ideal with wall limit for n=1

Coils in every other port, very close to plasma

n = 1 stable with wall/feedback to N’s around 5.0-6.0 n = 2 and 3 appear to have lower N limits in presence of wall, possibly blocking access to n = 1 limits

H-mode edge stability will depend on pedestal parameters; width, height, and location

Gro

wth

Rat

e, /s

N

N=4.2

Bialek, Columbia Univ.

Disruption ModelingExperimental database used to project for FIRE

Thermal quench time ≈ 0.2 ms

Ihalo/Ip TPF ≤ 0.5

dIp/dt rates for current quench ≤ 3 MA/ms (worst), and 1 MA/ms (typical)

TSC used to provide plasma evolutionHyper-resistivity for rapid j redistribution

Thalo and halo

Axisymmetric and zero-net current structures

Toroidal and poloidal currents

FIRE Transport and ConfinementEnergy Confinement Database

E98(y,2) = 0.144 M0.19 Ip0.93 BT

0.15 R1.97 0.58 n200.41 0.78 P-0.69 (m, MA, T, MW)

p*/E = 5

Zeff = 1.2-2.2 (fBe = 1-3%, fAr = 0-0.3%)

Pedestal Database (Sugihara, 2003)Pped(Pa) = 1.824104M1/3Ip2R-2.1a-0.573.81(1+2)-7/3(1+)3.41nped

-1/3(Ptot/PLH)0.144

----> Tped = 5.24 ± 1.3 keV----> ped??

L-H TransitionPLH(MW) = 2.84Meff

-1BT0.82nL20

0.58Ra0.81 (2000) ----> 26 MW in flattopPLH(MW) = 2.58Meff

-1BT0.60nL20

0.70R0.83 a1.04 (2002) ----> 18.5-25 MW in flattop

DN has less or equal PLH compared to favored SN (Carlstrom, DIII-D; NSTX; MAST)

H-L Transition & ELM’s Ploss > PLH although hysterisis exists in dataType I ELM’s typically require Ploss > 1.( )PLH, expts typically > 2PLH

Type II ELM’s require strong shaping, higher density, DN ---> reduced Pdiv, H98=1Type III ELM’s, near Ploss ≈ PLH, or high density, reduced H98Active methods ----> pellets, gas puffing, impurity seeding, ergodization

Pedestal Physics and ELM’sType I ELM trends

Reduced WELM/Wped with increasing *ped ----> inconsistent with higher Tped for

high Q

Reduced WELM/Wped with increasing ||i ----> inconsistent with higher Tped for

high Q

WELM/Wped correlated with Tped/Tped as nped varied, very little change in Nped/Nped

Type II ELM’sASDEX-U with DN and high n ----> H98 = 1-1.2 and reduction in divertor heat flux by 3

JET with high and high n ----> mixed Type I+II, no reduction in confinement and 3 reduction in ELM power loss

Pin

Wth

Prad

PELM

JET

POPCON Operating Space vs. ParametersT(0)/T, n(0)/n, p

*/E, H98, fBe, fAr

H98(y,2) must be ≥ 1.1 for robust operating space

1.5D Integrated Simulations H-mode

Tokamak Simulation Code (TSC)

Free-boundaryEnergy and current transportDensity profiles assumedGLF23 & MMM core energy transportAssumed pedestal height/locationICRF heating, data from SPRUCEBootstrap current, Sauter single ionPorcelli sawtooth modelCoronal equilibrium radiationImpurities with electron density profilePF coils and conducting structuresFeedback systems on position, shape, currentUse stored energy control

Snowmass E2 simulations for FIRECorsica, GTWHIST, Baldur, XPTOR

1.5D Integrated Simulations H-mode

FIRE H-mode, GLF23

1.5D Integrated Simulations H-modeFIRE Q Paux(MW) Tped(keV)

TSCGLF

10.3 13.5 4.5

10.0 7.5 3.8

10.0 10.0 4.1

10.0 12.5 4.4

10.0 15.0 4.7

10.0 20.0 5.4

BaldurMMM

4.5 30.0 2.5*

7.0 10.0 2.5*

XPTOR/12GLF

5.0 20.0 3.0

10.0 20.0 4.0

15.0 20.0 5.0

CorsicaGLF

4.0 12.5 2.5

6.0 12.5 4.0

10.0 12.5 5.0

0D Advanced Tokamak Operating SpaceScan ----> q95, n(0)/n, T(0)/T, n/nGr, N, fBe, fAr

Constrain ----> LH = 0.16, FW = 0.2, PLH ≤ 30 MW, P ≤ 30 MW, IFW = 0.2 MA,ILH = (1-fbs)Ip, QScreen ----> flattop(VV, TF, FW heating), Prad(div), Ppart(div), Paux< Pmax

Examples of FIRE Q=5 AT Operating Points That Obtain flat/J > 3

n n T T BT q95 Ip HH fGr fBS Pcd P zeff fBe fAr t/

0.5 2.60 1.5 8.17 6.5 4.25 4.25 1.71 0.8 0.80 27.5 27.8 2.08 1% .3% 3.58

0.5 2.93 2.0 7.28 6.5 4.25 4.25 1.57 0.9 0.80 30.9 31.4 1.77 1% .2% 3.95

0.75 3.10 1.5 7.83 6.5 3.75 4.82 1.46 0.9 0.80 33.1 36.5 1.89 2% .2% 3.07

0.75 2.91 1.0 7.71 6.5 4.00 4.52 1.62 0.9 0.85 24.7 28.6 1.77 1% .2% 3.52

0.75 3.23 1.5 7.00 6.5 4.00 4.52 1.54 1.0 0.85 27.5 32.0 2.08 1% .3% 4.40

0.75 2.44 1.5 8.90 6.5 4.25 4.25 1.74 0.8 0.91 16.0 28.0 2.20 2% .3% 3.65

1.00 3.49 1.0 7.35 6.5 3.50 5.16 1.36 1.0 0.83 32.6 38.6 1.77 1% .2% 3.00

1.00 3.26 1.0 7.60 6.5 3.75 4.82 1.54 1.0 0.89 23.9 30.1 2.01 3% .2% 4.00

1.00 2.44 1.5 9.59 6.5 4.00 4.52 1.65 0.8 0.95 13.6 31.5 2.32 3% .3% 3.29

HH < 1.75, satisfy all power constraints, Pdiv(rad) < 0.5 P(SOL)

1.5D Integrated Simulations AT-modeIp=4.5 MA Bt=6.5 T N=4.1 t(flat)/j=3.2 I(LH)=0.80P(LH)=25 MW

fBS=0.77 Zeff=2.3 q(0) =4.0 q(min) = 2.75 q(95) = 4.0 li = 0.42, = 4.7%, P = 2.35

1.5D Integrated Scenarios AT-mode

t = 12-41 s

1.5D Integrated Scenarios AT-moden/nGr = 0.85 n(0)/<n> = 1.4n(0) = 4.4x10^20Wth = 34.5 MJE = 0.7 s H98(y,2) = 1.7Ti(0) = 14 keV Te(0) = 16 keV(total) = 19 V-s, P = 30 MWP(LH) = 25 MWP(ICRF/FW) = 7 MW(up to 20 MW ICRF used in rampup)P(rad) = 15 MWZeff = 2.3

Q = 5I(bs) = 3.5 MA, I(LH) = 0.80 MA I(FW) = 0.20 MA, t(flattop)/j=3.2

Perturbation of AT-mode Current Profile5 MW perturbation to PLH

Flattop time is sufficient to examine CD control

t = 12 st = 25 s

t = 25 st = 41 s

Conclusions

• The FIRE device design provides sufficient/flexible/relevant operating space to examine burning plasma physics– Sufficient to provide burning conditions (Q ≥ 10 inductive and Q ≥ 5

AT, does not preclude ignition)– Flexible to accommodate uncertainty and explore various physics

regimes– Relevant to power plant plasma physics and engineering design

• The subsystems on FIRE, within their operating limits, are suitable to examine burning plasma physics ----> subject to R&D in some cases– Auxiliary heating/CD– Particle fueling and pumping– Divertor/baffle and FW PFC’s– Magnets– Diagnostics

Conclusions• Burning plasma conditions can be accessed and studied in

both standard H-mode and Advanced Tokamak modes. The range of AT performance has been expanded significantly since Snowmass– FIRE can reach 1-5 j, and examine current profile control– Design improvement to FW tiles could extend flattop times

further – FIRE can reach 80-90% of ideal with wall limit, with RWM

feedback– FIRE can reach high IBS/IP (77% in 1.5D simulation)– Identified that radiative mantle/divertor solutions significantly

expand operating space– FIRE will pursue Fe shims for AT operation

• The physics basis for FIRE’s operation is based on current experimental and theoretical results, and projections based on these continue to provide confidence that FIRE will achieve the required burning plasma performance

Issues/Further Work

• Magnets– Ripple reduction, design Fe shims for AT mode– Continue equilibrium analysis– Complete plasma breakdown and early startup– Complete internal control coil analysis– RWM coil design/integration into port plugs, time dependent analysis– Error field control coil design

• Heating and CD– Continue ICRF antenna design, disruption loads, neutron/surface heating– Engineering of 4 strap expanded antenna option– More detailed design of LH launcher, disruption loads, neutron/surface heating– Complete 2D FP/expanded LH calculations for FIRE specific cases– Continue examination of EC/OKCD for NTM suppression in AT mode– Pursue dynamic simulations/PEST3 analysis of LH NTM stabilization for both H-

mode and AT-mode

Issues/Further Work• Power Handling

– Pulse length limitations from VV nuclear heating, design improvements– FW tile design, material choices, impacts on magnetics– Continue divertor analysis, UEDGE and neutrals analysis for integrated heat load,

pumping,and core He concentration solutions– Continue examination of ITPA ELM results and projections, encourage DN strong

triangularity experiments– DN up-down imbalance, implications for divertor design (lots of work on DII-D)– Disruption mitigation strategies, experiments

• Particle Handling– Continue pellet and gas fueling analysis in high density regime of FIRE– Neutrals analysis for pumping– Be behavior as FW material and intrinsic impurity– Impurity injection, core behavior, and controllability– Particle control techniques: puff and pump, density feedback control, auxiliary

heating to pump out core, etc.– Wall behavior, no inner divertor pumping, what are impacts?

Issues/Further Work

• MHD Stability– LH stabilization of NTM’s, analysis and experiments (JET, JT-60U and C-Mod)– Examine plasmas that appear not to be affected by NTM’s (current profile)– Early (before they are saturated) stabilization of NTM’s with EC/OKCD– Continue to develop RWM feedback scheme in absense of rotation– Identify impact of n=2,3 modes in wall/feedback stabilized plasmas– Examine impact of no external rotation source on transport, resistive and ideal

modes– Alfven eigenmodes/energetic particle modes, onset and accessibility in FIRE

• Plasma Transport and Confinement– Continue core turbulence development for H-mode, ITPA– Establish AT mode transport features, ITB onset, ITPA– Pedestal physics and projections, and ELM regimes, ITPA– Impact of DN and strong shaping on operating regimes, Type II ELMs– Improvements to global energy confinement scaling, single device trends– Expand integrated modeling of burning plasmas