FIRE Physics Basis

1
FIRE Physics Basis

• C. Kessel for the FIRE Team
• Princeton Plasma Physics Laboratory
• FIRE Physics Validation Review
• March 30-31, 2004
• Germantown, MD

2
FIRE Description
R 2.14 m, a 0.595 m, ?x 2.0, ?x 0.7, Pfus
150 MW

• AT-Mode
• IP 4.5 MA
• BT 6.5 T
• ?N 4.2
• ? 4.7
• ?P 2.35
• ???? 0.21
• q(0) 4.0
• q95, qmin 4.0,2.7
• li(1,3) 0.52,0.45
• Te,i(0) 15 keV
• ?Te,i? 6.8 keV
• n20(0) 4.4
• n(0)/?n? 1.4
• p(0)/?p? 2.5
• n/nGr 0.85
• Zeff 2.2
• fbs 0.78
• Q 5

• H-mode
• IP 7.7 MA
• BT 10 T
• ?N 1.80
• ? 2.4
• ?P 0.85
• ???? 0.075
• q(0) lt 1.0
• q95 3.1
• li(1,3) 0.85,0.66
• Te,i(0) 15 keV
• ?Te,i? 6.7 keV
• n20(0) 5.3
• n(0)/?n? 1.15
• p(0)/?p? 2.4
• n/nGr 0.72
• Zeff 1.4
• fbs 0.2
• Q 12

VV
baffle
divertor
passive plate
plasma
port
3
FIRE Magnet Layout
Error field correction coils
PF4
PF1,2,3
TF Coil
CS3
Fe shims
PF5
CS2
CS1
Fast vertical and radial position control coil
RWM feedback coil
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FIRE Magnets
TF Coils Limit 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-mode 8 ? loss AT-mode
(Fe shims) PF Coils Provide H-mode
operation 0.55 li(3) 0.85 (SOB,EOB) 0.85
li(3) 1.15 (SOH,EOH) ?ref-5 ?(Wb)
?ref5 1.5 ?N 3.0 ??ramp 40 V-s, ??flat 3
V-s Provide AT-mode operation 0.35 li(3)
0.65 (SOB EOB) 2.5 ?N 5.0 7.5
?flattop(Wb) 17.5 Ip 5.0 MA ??ramp 20 V-s
PF1,2,3
PF4
CS3
CS2
PF5
CS1
5
FIRE Magnets
Vertical stability Cu passive plates, 2.5 cm
thick For most unstable plasmas (full elongation
and low pressure), over the range 0.7 lt li(3) lt
1.1, the stability factor is 1.3 lt fs lt 1.13 and
growth time is 43 lt tg(ms) lt 19 Internal Control
Coils Fast vertical position control Fast radial
position control (antenna) Startup assist Error
Correction Coils Static to slow response Correct
PF and TF coil, lead, etc. misalignments
ITER Error Coils
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FIRE Magnets
Resistive Wall Mode Coils DIII-D Modes are
detectable at the level of 1G C-coils produce
about 50 times this field The necessary frequency
depends on the wall time for the n1 mode (which
is 5 ms in DIII-D) and they have ??wall
3 FIRE FIRE has approximately 3-4 times the
plasma current, so we might be able to measure
down to 3-4 G If we try to guarantee at least 20
times this value from the feedback coils, we must
produce 60-80 G at the plasma These fields
require approximately I f(d,Z,?)Br/?o 5-6.5
kA Assume we also require ??wall 3 Required
voltage would go as V 3?o(2d2Z)NI/??wall
0.25 V/turn
ICRF Port Plug
RWM Coil
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FIRE Heating and CD
ICRF (20 MW, 70-115 MHz) Ion heating _at_ 10 T He3
minority and 2T at 100 MHz Ion heating _at_ 6.5 T H
minority and 2D at 100 MHz Electron heating/CD _at_
6.5 T 70-75 MHz, ?20 0.14-0.21 A/W-m2 LHCD
(30MW, 5 GHz) n 1.8-2.5, ?n 0.3 NTM
control _at_ 10 T Bulk CD/NTM _at_ 6.5 T ?20 0.16
A/W-m2 ECCD (??MW, 170 GHz) LFS, O-mode,
fundamental NTM control _at_ 6.5 T ?20 0.004
A/W-m2 (at 149 GHz)
??ce170 GHz
?pe?ce
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ICRF Heating and CD
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
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Power Handling
First wall Surface heat flux Plasma radiation,
Qmax P? Paux Volumetric heating Nuclear
heating, qmax qpeak(Z0) VV, Cladding, Tiles,
Magnets. Volumetric heating Nuclear heating,
qmax qpeak(Z0) Divertor Surface heat
flux Particle heat flux, Qmax
PSOL/Adiv(part) Radiation heat flux, Qmax
PSOL/Adiv(rad) Volumetric heating Nuclear
heating, qmax qpeak(divertor)
VV
Clad
Tile
plasma
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Power Handling
Pulse length limitations VV nuclear heating
(stress limit), 4875 MW-s -----gt Pfus
(qVVnuclear) FW Be coating temperature, 600oC
-----gt QFW Pfus (qBenuclear) TF coil heating,
373oK -----gt BT Pfus (qCunuclear) PF Coil
heating-AT-mode, 373oK -----gt Ip, li, ?p, and ?
(not limiting) Component limitations Particle
power to outboard divertor lt 28 MW Radiated
power on (innerouter) divertor/baffle lt 6-8 MW/m2
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Power Handling/Operating Space
FIRE H-mode Operating Space ?N limited by NTM or
ideal MHD with NTM suppression -----gt maximum
Pfus Higher radiated power in the divertor
allows more operating space, mainly at higher
?N -----gt maximum Pfus Majority of operating
space limited by TF coil flattop -----gt ?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
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Power Handling/Operating Space
FIRE AT-mode Operating Space ?N is limited by
ideal MHD w/wo RWM feedback -----gt maximum
Pfus Higher radiated power in the divertor
allows more operating space, mainly at higher
?N -----gt maximum Pfus Majority of operating
space limited by VV nuclear heating -----gt
?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
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FIRE Particle Handling
Cryopumping in slanted ports Midplane 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
VHFS 125 m/s Parks, 2003
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MHD Stability
H-mode Sawtooth ---gt unstable, weak impact on
burn, coupling to global modes? NTMs ---gt
unstable or stable?, LHCD ? stabilization,
reduce ?N if near threshold, experiments with
little or no NTM impact (DIII-D, JET,
ASDEX-U) Ideal MHD ---gt over range of profiles
?N (n1 or 8) 3 AT-mode NTMs ---gt unstable or
stable? q(?) gt 2 everywhere, r/a(qmin) 0.8,
ECCD/OKCD, LHCD multiple spectra Ideal MHD ---gt
no wall/feedback, ?N (n1) 2.5-2.8
---gt with wall/feedback, VALEN
analysis indicates 80-90 of with-
wall ?N-limit (5-6), however,
n2,3 have lower ?N-limits? Other MHD
issues Ballooning/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
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FIRE MHD Stability
TSC-LSC
(3,2) surface 12.5 MW 0.65 MA n/nGr 0.4 Q
6.8
Neoclassical Tearing Modes H-mode Threshold for
NTMs is uncertain Sawteeth and ELMs are
expected to be present and can drive
NTMs Typical operating point is at low ?N and
?P Can lower ?N further if near threshold Lower
Hybrid CD at the rational surfaces Compass-D
demonstrated LH stabilization Analysis by Pletzer
and Perkins showed stabilization was feasible
(PEST3) Lowers Q(Pfus/Paux) EC methods require
high frequencies at FIRE field and densities
----gt 280 GHz DIII-D (Luce) ?N 3, NTM weak
impact ASDEX-U, JET (Gunter) frequently
interrupted NTM
confinement degradation
JET
normal
FIR-NTM
Weak NTM, FIR-NTM
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MHD Stability
RWM Stabilization AT-mode RWM stabilization
with feedback coils, VALEN analysis indicates
80-90 of ideal with wall limit for n1 Coils in
every other port, very close to plasma n 1
stable with wall/feedback to ?Ns 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
Bialek, Columbia Univ.
Growth Rate, /s
?N4.2
?N
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Disruption Modeling
Experimental 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 evolution
Hyper-resistivity for rapid j redistribution Thal
o and ?halo Axisymmetric and zero-net current
structures Toroidal and poloidal currents
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FIRE Transport and Confinement
Energy Confinement Database ?E98(y,2) 0.144
M0.19 Ip0.93 BT0.15 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)
1.824?104M1/3Ip2R-2.1a-0.57?3.81(1?2)-7/3(1?)3.4
1nped-1/3(Ptot/PLH)0.144 ----gt Tped 5.24 1.3
keV ----gt ?ped?? L-H Transition PLH(MW)
2.84Meff-1BT0.82nL200.58Ra0.81 (2000) ----gt 26
MW in flattop PLH(MW) 2.58Meff-1BT0.60nL200.70R0
.83 a1.04 (2002) ----gt 18.5-25 MW in flattop DN
has less or equal PLH compared to favored SN
(Carlstrom, DIII-D NSTX MAST) H-L Transition
ELMs Ploss gt PLH although hysterisis exists in
data Type I ELMs typically require Ploss gt 1.(
)?PLH, expts typically gt 2?PLH Type II ELMs
require strong shaping, higher density, DN ---gt
reduced Pdiv, H981 Type III ELMs, near Ploss
PLH, or high density, reduced H98 Active methods
----gt pellets, gas puffing, impurity seeding,
ergodization
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Pedestal Physics and ELMs
Type I ELM trends Reduced ?WELM/Wped with
increasing ?ped ----gt inconsistent with higher
Tped for high Q Reduced ?WELM/Wped with
increasing ?i ----gt inconsistent with higher
Tped for high Q ?WELM/Wped correlated with
?Tped/Tped as nped varied, very little change in
?Nped/Nped
Type II ELMs ASDEX-U with DN and high n ----gt
H98 1-1.2 and reduction in divertor heat flux
by 3? JET with high ? and high n ----gt mixed
Type III, no reduction in confinement and 3?
reduction in ELM power loss
Pin
JET
PELM
Wth
Prad
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POPCON Operating Space vs. Parameters
T(0)/?T?, n(0)/?n?, ?p/?E, H98, fBe, fAr
H98(y,2) must be 1.1 for robust operating space
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1.5D Integrated Simulations H-mode
Tokamak Simulation Code (TSC) Free-boundary Energ
y and current transport Density profiles
assumed GLF23 MMM core energy transport Assumed
pedestal height/location ICRF heating, data from
SPRUCE Bootstrap current, Sauter single
ion Porcelli sawtooth model Coronal equilibrium
radiation Impurities with electron density
profile PF coils and conducting
structures Feedback systems on position, shape,
current Use stored energy control Snowmass E2
simulations for FIRE Corsica, GTWHIST, Baldur,
XPTOR
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1.5D Integrated Simulations H-mode
FIRE H-mode, GLF23
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1.5D Integrated Simulations H-mode
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0D Advanced Tokamak Operating Space
Scan ----gt q95, n(0)/?n?, T(0)/?T?, n/nGr, ?N,
fBe, fAr Constrain ----gt ?LH 0.16, ?FW 0.2,
PLH 30 MW, P 30 MW, IFW 0.2 MA, ILH
(1-fbs)Ip, Q Screen ----gt ?flattop(VV, TF, FW
heating), Prad(div), Ppart(div), Pauxlt Pmax
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Examples of FIRE Q5 AT Operating Points That
Obtain ?flat/?J gt 3
HH lt 1.75, satisfy all power constraints,
Pdiv(rad) lt 0.5 P(SOL)
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1.5D Integrated Simulations AT-mode
fBS0.77 Zeff2.3 q(0) 4.0 q(min) 2.75
q(95) 4.0 li 0.42, ? 4.7, ?P 2.35
Ip4.5 MA Bt6.5 T ?N4.1 t(flat)/?j3.2
I(LH)0.80 P(LH)25 MW
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1.5D Integrated Scenarios AT-mode
t 12-41 s
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1.5D Integrated Scenarios AT-mode
Q 5 I(bs) 3.5 MA, I(LH) 0.80 MA I(FW)
0.20 MA, t(flattop)/?j3.2
n/nGr 0.85 n(0)/ltngt 1.4 n(0) 4.4x1020 Wth
34.5 MJ tE 0.7 s H98(y,2) 1.7 Ti(0) 14
keV Te(0) 16 keV Dy(total) 19 V-s, Pa 30
MW P(LH) 25 MW P(ICRF/FW) 7 MW (up to 20 MW
ICRF used in rampup) P(rad) 15 MW Zeff 2.3
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Perturbation of AT-mode Current Profile
5 MW perturbation to PLH Flattop time is
sufficient to examine CD control
t 12 s t 25 s
t 25 s t 41 s
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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 ----gt subject to RD in some cases
• Auxiliary heating/CD
• Particle fueling and pumping
• Divertor/baffle and FW PFCs
• Magnets
• Diagnostics

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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 FIREs 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

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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

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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?

34
Issues/Further Work

• MHD Stability
• LH stabilization of NTMs, analysis and
  experiments (JET, JT-60U and C-Mod)
• Examine plasmas that appear not to be affected by
  NTMs (current profile)
• Early (before they are saturated) stabilization
  of NTMs with EC/OKCD
• Continue to develop RWM feedback scheme in
  absense of rotation
• Identify impact of n2,3 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