Optimization of a Highb SteadyState Tokamak Burning Plasma Experiment Based on a Highb SteadyState T

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Optimization of a High-b Steady-State Tokamak
Burning Plasma Experiment Based on a High-b
Steady-State Tokamak Power Plant
D. M. Meade, C. Kessel, S. Jardin Princeton
Plasma Physics Laboratory
Presented at IEA Workshop on Optimization of
High-b Steady-State Tokamaks General Atomics
February 14, 2005
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Tokamak Based Power Plant Studies have Identified
Attractive High-b Steady-State Configurations
with A 4
Three decades of systematic studies in the US
have surveyed the range of possibilities
available for a tokamak power plant and have
identified the ARIES-RS/AT (A 4) designs as
the most attractive possibilities. Other
studies favoring highish aspect ratio for high-b
steady-state include TPX (A 4.5), ITER-HARD (A
4), ASSTR (A 4) The FIRE design studies
initiated in 1999 adopted the ARIERS/AT physics
and plasma technology design characteristics
including
Strong shaping Double null dx 0.7, kx
2, Aspect ratio 4 Reactor level BT 6 -
10 T and plasma density 2 - 4 x 1020m-3
LHCD/ICFWCD - no momentum input All metal
PFCs W divertor Internal fast control coils
RWM coils integrated into FW of port plugs -
LN cooled coils provide sufficient pulse length
and small size low cost
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Optimization of Cu Coil BPX (e,.g, FIRE)
Optimization Depends on Goals and Constraints
Realistic engineering constraints must be
imposed Optimization of inductively-driven
BPX with Cu Coil (e,.g, FIRE) 1991 CIT Study
(LLNL Super Code-Galumbos) W. Reiersen 2000
FIRE (FIRE Sale) J. Schultz 2001 FIRE (BPSC) S.
Jardin,C. Kessel, D. Meade, C. Neumeyer
Optimization of High-b Steady-State Modes in FIRE
2002 SOFE Meeting FIRE AT C. Kessel 2002/2004
IAEA FIRE D. Meade et al
References 1. J. Galumbos et al Fusion Tech. 13,
93, 1988 2. W. Reiersen 3. J. Schultz - 4. S.
Jardin, C. Kessel et al Fusion Science and
Technology 43, 161 2003 5. A High-Aspect-Ratio
Design for ITER, J. C. Wesley et al Fusion Tech.
21, 1380 1992. 6. Y. Seki et al., (1991). Rep.
JAERI-M 91-081, JAERI. Naka.
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CIT Optimization Using Super Code 1989
Compact Ignition Tokamak Optimized at A 3.5
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The Systems Code was Updated and Calibrated Based
on 3-D Finite Element Stress Calculations for
FIRE.
Confinement (Elmy H-mode) ITER98(y,2) ??E
0.144 I0.93 R1.39 a0.58 n200.41 B0.15 Ai0.19
?0.78 P heat -0.69 H(y,2) Density Limit
n20 Threshold Pth (2.84/Ai) n200.58 B0.82 R
a0.81 MHD Stability ?N ?? / (IP/aB) 3.0 PAUX, Q PFUSION/PAUX, qCYL or qMHD,, ZEFF
all held fixed Engineering Constraints 1. Flux
swing requirements in OH coil (V-S) 2. Coil
temperature not exceed 373o K 3. Coil stresses
remain within allowables Configuration Concept
1. OH coils not linking TF coils, or 2. OH
coils linking TF coilsST-like
Kessel, Jardin 2002
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Optimization of Cu Coil BPX (e,.g, FIRE) Using
BPSC
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Optimization at Smaller Size and Higher Aspect
Ratio as Confinement Improves
Major Radius (m)
10T
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Optimization is not Sensitive to Variation of
Elongation with Aspect Ratio
Major Radius (m)
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bN 1.8 Pf/V 5.5 MWm-3 fbs 25
Normalized pulse length (tCR)in FIRE is the same
as ITER
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Optimization of High-b Steady-State Modes in a
Cu Coil BPX (e,.g, FIRE)
Optimization of AT Modes in a specific FIRE
(Fixed A, R, B Systems Code to calculate a large data base( 50,
000) of possible solutions as parameter space is
scanned. Impose engineering constraints on
pulse length (TF ohmic and nuclear heating,
divertor target and baffle heat loads, vacuum
vessel nuclear heating and first wall surface
heating) to define operating space. Use
J_solver and PEST to validate stability and
required current profiles. Use TSC to
confirm evolution of integrated discharge.
Steady-state 100 non-inductive, dq/q for several tCR , tdiv, tFW
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0-D 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)/, T(0)/, n/nG, ?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)
• P(SOL)-Pdiv(rad)
• Qdiv(rad)

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FIREs Q 5 AT Operating Space
A data base of 50,000 operating points is
calculated with 0-D code Engineering
constraints are imposed to generate the
operational boundaries shown below Potential
operating points are examined in more
detail-PEST, TSC, etc
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FIRE AT Mode Operating Range is Limited by
Nuclear Heating of Vac Vessel First Wall Not by
Cu Coils
Nominal operating point Q 5 Pf 150 MW,
Pf/Vp 5.5 MWm-3 (ARIES) steady-state
4 to 5 tCR Physics basis improving (ITPA)
required confinement H factor and bN
attained transiently C-Mod LHCD experiments
will be very important First Wall is the main
limit Improve cooling revisit FW design
Opportunity for additional improvement
(optimization).
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Steady-State High-b Advanced Tokamak Discharge
on FIRE
Pf/V 5.5 MWm-3 Gn 2 MWm-2 B 6.5T bN 4.1,
bt 5 fbs 77 100 non-inductive Q 5 H98
1.7 n/nGW 0.85 Flat top Duration 48 tE
10 tHe 4 tcr
FT/P7-23
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Additional Opportunities to Optimize FIRE for the
Study of ARIES AT Physics and Plasma
Technologies
ARIES AT (bN 5.4, fbs 90)
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FIRE-AT Approaches the Parameters Envisioned for
ARIES-Power Plant Plasmas
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Concluding Remarks
FIRE is very close to the optimum aspect ratio
and size for an inductively-driven H-Mode burning
plasma experiment using LN-cooled coils. The
present FIRE configuration is also capable of
producing AT plasmas with characteristics
approaching those of ARIES-RS with pulse lengths
sufficient to study High-b Steady-state burning
plasmas with fusion power densities of 5 MW
m-3. The present FIRE AT regimes are limited
by the first wall and vacuum vessel and not the
TF coil. - improve FW and Vac Vessel cooling
6 tCR - change TF conductor to OFHC (Bt
7T) 12 tCR A bottoms up optimization
of a FIRE for AT operation only has not been
done, but the present case must be fairly close
to the optimum.