FIRE Advanced Tokamak Progress

1
FIRE Advanced Tokamak Progress

• C. Kessel
• Princeton Plasma Physics Laboratory
• NSO PAC 2/27-28/2003, General Atomics

• 0D Operating Space
• PF Coils
• Equilibrium/Stability
• ECCD/Neoclassical Tearing Modes
• RWM Stabilization
• ICRF, FWCD, LHCD
• TSC-LSC Simulations
• 8. Further Work ---gt PVR

2
ARIES-AT Provides a Long Term Target for Advanced
Tokamaks
FIRE-AT will need to show how close we can get to
this configuration thru control in a burning
plasma Steady state Strong plasma
shaping Large bootstrap fraction, minimal
CD High ? Transport that supports high fBS and
high ? Plasma edge solution that supports CD,
power handling, divertor solution
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0D Operating Space Analysis for FIRE AT

• Heating/CD Powers
• ICRF/FW, 30 MW
• LHCD, 30 MW
• Using CD efficiencies
• ?(FW)0.20 A/W-m2
• ?(LH)0.16 A/W-m2
• P(FW) and P(LH) determined at r/a0 and r/a0.75
• I(FW)0.2 MA
• I(LH)Ip(1-fbs)
• Scanning Bt, q95, n(0)/ltngt, T(0)/ltTgt, n/nGr, ?N,
  fBe, fAr

• Q5
• Constraints
• ?(flattop)/?(CR) determined by VV nuclear heat
  (4875 MW-s) or TF coil (20s at 10T, 50s at 6.5T)
• P(LH) and P(FW) max installed powers
• P(LH)P(FW) Paux
• Q(first wall) lt 1.0 MW/m2 with peaking of 2.0
• P(SOL)-Pdiv(rad) lt 28 MW
• Qdiv(rad) lt 8 MW/m2

4
FIREs Q5 AT Operating Space
Access to higher tflat/?j decreases at higher ?N,
higher Bt, and higher Q, since tflat is set by VV
nuclear heating Access to higher radiated power
fractions in the divertor enlarges operating
space significantly
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FIREs AT Operating Space
Q 5-10 accessible ?N 2.5-4.5 accessible fbs
50-90 accessible tflat/tj 1-5
accessible If we can access.. H98(y,2)
1.2-2.0 Pdiv(rad) 0.5-1.0 P(SOL) Zeff
1.5-2.3 n/nGr 0.6-1.0 n(0)/ltngt 1.5-2.0
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Examples of Q5 AT Points That Obtain ?flat/?J gt 3
HH lt 1.75, satisfy all power constraints,
Pdiv(rad) lt 0.5 P(SOL)
?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
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PF Coils Must Sustain AT Plasmas with Low li and
High ?
Ip4.5-5.5 MA, Bt6.5-8.5T 100 non-inductive in
flattop Ip can not be too low or well loose
too many alphas from ripple Inductive
non-inductive rampup ----gt consumes 19-22 V-s,
what is final flux state?? Flattop times 16-50s
(from Pfusion of 300-100 MW) and TF coil Low
li(3) 0.42, ?N4.2 Divertor coils are driven to
high currents
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PF Coil Capability for AT Modes

• Advanced tokamak plasmas
• Range of current profiles 0.35 lt li(3) lt 0.55
• Range of pressures 2.50 lt ?N lt 5.0
• Range of flattop flux states chosen to minimize
  heating and depends on flattop time (determined
  by Pfusion)
• Ip limited to 5.5 MA
• Lower li operating space led to redesign of
  divertor coils
• PF1 and PF2 changed to 3 coils and total
  cross-section enlarged
• Presently examining magnet stresses and heating
  for AT scenarios

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Neo-Classical Tearing Modes at Lower Bt for FIRE
AT Modes
Target Bt6.5-7 T for NTM control, to utilize 170
GHz from ITER RD Must remain on LFS for
resonance ECCD efficiency, can local ?e be high
enough to avoid trapping boundary??
Avoid NTMs with j profile and qgt2.0 or do we
need to suppress them??
Ro
Roa
Bt6.5 T
?
fce182
fce142
170 GHz
Ro
Roa
Bt7.5 T
?
?
fce210
fce164
200 GHz
Ro
Roa
Bt8.5 T
?
fce190
fce238
Can we rely on OKCD to suppress NTMs far
off-axis on LFS versus ECCD ?? (enhanced Ohkawa
affect at plasma edge)
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J. Decker, APS 2002,MIT
OKCD allows LFS EC deposition, with similar A/W
as ECCD on HFS
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Comments on ECCD in FIRE

• ASDEX-U shows that 3/2 island is suppressed for
  about 1 MW of power with IECCD/Ip 1.6, giving
  0.013 A/W
• Ip0.8 MA and ?N2.5
• DIII-D shows that 3/2 island is suppressed for
  about 1.2-1.8 MW with jEC/jBS 1.2-2.0
• Ip1.0-1.2 MA, ?N2.0-2.5
• OKCD analysis of Alcator-CMOD gives about 0.0056
  A/W
• FIREs current requirement should be about 15
  times higher than ASDEX-U (scaled by Ip and ?N2)
• Need about 200 kA, which would require about 35
  MW?? Early detection reduces power alot according
  to ITER
• Do we need less current for 5/2 or 3/1, do we
  need to suppress them??
• Is 170 GHz really the cliff in EC technology??

MIT, short pulse results
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Updating AT Equilibrium Targets Based on TSC-LSC
Equilibrium
TSC-LSC equilibrium Ip4.5 MA Bt6.5 T q(0)3.5,
qmin2.8 ?N4.2, ?4.9, ?p2.3 li(1)0.55,
li(3)0.42 p(0)/?p?2.45 n(0)/?n?1.4 Stable
n? Stable n1,2,3 with no wall
vV/Vo
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Original AT Target Equilibrium for FIRE
This needs to be revisited with Ip4.5 MA and
Bt6.5 T
q(min) 2.1-2.2 r/a(qmin) 0.8 n(0)/ltngt
1.5 Ip 5.5 MA Bt 8.5 T No wall
stabilization bN 2.5 n1 RWM stabilized bN
3.65
bN 3.65, fbs lt 0.75
bN 2.5, fbs lt 0.55
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Stabilization of n1 RWM is a High Priority on
FIRE
Feedback stabilization analysis with VALEN shows
strong improvement in ?, taking advantage of
DIII-D experience, most recent analysis indicates
?N(n1) can reach 4.2
What is impact of n2??
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Ideal wall n1 limit
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FIRE Uses ICRF Ion Heating for Its Reference and
AT Discharges

• ICRF ion heating
• 80-120 MHz
• 2 strap antennas
• 4 ports (2 additional reserved)
• 20 MW installed (10 MW additional reserved)
• He3 minority and 2T heating
• Frequency range allows heating at a/2 on HFS and
  LFS (C-Mod ITB)

• Full wave analysis
• SPRUCE in TRANSP
• Using n(He3)/ne 2
• n20(0) 5.3, ltn20gt 4.4
• PICRF 11.5 MW, ? 100 MHz
• THe3(0) 10.2 keV
• Pabs(He3) 60
• Pabs(T) 10
• Pabs(D) 2
• Pabs(elec) 26

Antenna design ---gtD. Swain, ORNL
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ICRF/FW Viable for FIRE On-Axis CD
Calculations assume same ICRF ion heating system
frequency range, approximately 40 of power
absorbed on ions, can provide required AT on-axis
current of 0.3-0.4 MA with 20 MW (2 strap
antennas)
PICES (ORNL) and CURRAY(UCSD) analysis f
110-115 MHz n 2.0 n(0) 5x1020 /m3 T(0)
14 keV 40 power in good part of spectrum (2
strap) ----gt 0.02-0.03 A/W CD efficiency with 4
strap antennas is 50 higher Operating at lower
frequency to avoid ion resonances, vph/vth??
E. Jaeger, ORNL
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Benchmarks for LHCD Between LSC and ACCOME
(Bonoli)
Trapped electron effects reduce CD
efficiency Reverse power/current reduces forward
CD Recent modeling with CQL and ACCOME/LH19 will
improve CD efficiency, but right now.. Bt8.5T
----gt 0.25 A/W-m2 Bt6.5T ----gt 0.16 A/W-m2 FIRE
has increased the LH power from 20 to 30 MW
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HFS Pellet Launch and Density Peaking ---gt Needs
Strong Pumping
Simulation by W. Houlberg, ORNL, WHIST
FIRE reference discharge with uniform pellet
deposition, achieves n(0)/ltngt 1.25
P. T. Lang, J. Nuc. Mater., 2001, on ASDEX and
JET L. R. Baylor, Phys. Plasmas, 2000, on DIII-D
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HFS Launch V125 m/s, set by ORNL pellet tube
geometry Vertical and LFS launch access higher
velocities
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TF Ripple and Alpha Particle Losses
TF ripple very low in FIRE ?(max) 0.3
(outboard midplane) Alpha particle collisionless
collisional losses 0.3 for reference ELMy
H-mode For AT plasmas alpha losses range from
2-8 depending on Ip and Bt ----gt are Fe inserts
required for AT operation??? Optimize for Bt6.5T
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Fe Shims for Ripple Reduction in FIRE
TF Coil
Fe Shims
Outer VV
Inner VV
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TSC-LSC Simulation of Burning AT Plasma in FIRE

• Bt6.5 T, Ip4.5 MA
• q(0) 4.0, q(min) 2.75, q(95) 4.0, li 0.42
• b 4.7 , bN 4.1, bp 2.35
• n/nGr 0.85, n(0)/ltngt 1.47
• n(0) 4.4x1020, n(line) 3.5, n(vol) 3.0
• 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
• Q 5
• I(bs) 3.5 MA, I(LH) 0.80 MA, I(FW) 0.20 MA
• t(flattop)/?j3.2

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TSC-LSC Simulation of Q5 Burning AT Plasma
Ip4.5 MA, Bt6.5 T, ?N4.1, t(flat)/?j3,
I(LH)0.80, P(LH)25 MW fBS0.77, Zeff2.3,
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TSC-LSC Simulation of Q5 AT Burning Plasma
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TSC-LSC Simulation of Q5 AT Burning Plasma
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AT Physics Capability on FIRE
Control
Strong plasma shaping and control Pellet
injection, divertor pumping, impurity
injection FWCD (electron heating) on-axis, ICRF
ion heating off-axis LHCD (electron heating)
off-axis ECCD (LFS, electron heating) off-axis,
MHD control RWM MHD feedback control NBI ??
(need to examine for AT parameters!!) t(flattop)/
t(curr diff) 1-5 Diagnostics
MHD J Profile P-profile Rotation
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Ongoing Advanced Tokamak Work ---gt PVR

• Establish PF Coil operating limits
• Revisit Equilibrium/Stability Analysis
• Use recent GLF23 update in AT scenarios
• LHCD efficiency updates
• EC with FIREs parameters
• Orbit calculations of lost alphas for scenario
  plasmas
• RWM coil design in port plugs and RF ports
• Determine possible impact of n2 RWM on access to
  high ?N
• Examine NBI for FIRE AT parameters