Advanced Tokamak Regimes

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Advanced Tokamak Regimes in the Fusion Ignition
Research Experiment (FIRE)
Dale Meade for the FIRE Collaboration
30th Conference on Controlled Fusion and Plasma
Physics St. Petersburg, Russia July 10, 2003
http//fire.pppl.gov
FIRE Collaboration
AES, ANL, Boeing, Columbia U., CTD, GA, GIT,
LLNL, INEEL, MIT, ORNL, PPPL, SNL, SRS, UCLA,
UCSD, UIIC, UWisc,
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Topics to be Discussed

• Vision for Magnetic Fusion Power Plant
• Conventional Mode Operation in FIRE
• Advanced Mode Operation in FIRE
• O-D Systems analysis
• 1.5-D Tokamak Code Simulation
• RWM Stabilization Concept
• Issues Needing RD
• Concluding Remarks

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ARIES Economic Studies have Defined Requirements
for an Attractive Fusion Power Plant
Plasma Exhaust Pheat/Rx 100MW/m Helium
Pumping Tritium Retention
High Power Gain Q 25 - 50 ntET 6x1021
m-3skeV Pa/Pheat fa 90
Plasma Control Fueling Current Drive RWM
Stabilization
High Power Density 6 MW-3 10 atm
Steady-State 90 Bootstrap
Significant advances (gt 10) are needed in each
area. In addition, the plasma phenomena are
non-linearly coupled.
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Attractive Reactor Regime is a Big Step
From Today
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Fusion Ignition Research Experiment (FIRE)

• R 2.14 m, a 0.595 m
• B 10 T, ( 6.5 T, AT)
• Ip 7.7 MA, ( 5 MA, AT)
• PICRF 20 MW
• PLHCD 30 MW (Upgrade)
• Pfusion 150 MW
• Q 10, (5, AT)
• Burn time 20s (2 tCR-Hmode)
• 40s (lt 5 tCR-AT)
• Tokamak Cost 350M (FY02)
• Total Project Cost 1.2B (FY02)

1,400 tonne
Mission to attain, explore, understand and
optimize magnetically-confined fusion-dominated
plasmas
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Characteristics of FIRE

• 40 scale of ARIES plasma xsection
• All metal PFCs
• Actively cooled W divertor
• Be tile FW, cooled between shots
• T inventory TFTR
• LN cooled BeCu/OFHC TF
• no neutron shield, small a
• 3,000 full pulses
• 30,000 2/3 pulses
• X3 repetition rate since SNMS
• Site needs comparable to previous
• DT tokamaks.

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FIRE Plasma Regimes
H-Mode AT(ss) ARIES-RS/AT R/a 3.6 3.6
4 B (T) 10 6.5 8 - 6 Ip (MA)
7.7 5 12.3-11.3 n/nG 0.7 0.85 1.7-0.85 H(
y,2) 1.1 1.2 1.7 0.9 - 1.4 bN 1.8
4.2 4.8 - 5.4 fbs , 25 77 88 -
91 Burn/tCR 2 3 - 5 steady
Operating Modes Elmy H-Mode Improved
H-Mode Reversed Shear AT - OH assisted -
steady-state (100 NI)
H-mode facilitated by dx 0.7, kx 2, n/nG
0.7, DN reduction of Elms.
AT mode facilitated by strong shaping, close
fitting wall and RWM coils.
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FIRE Plasma Systems are Similar to ARIES-AT

• kx 2.0, dx 0.7
• Double null divertor
• Very low ripple 0.3 (0.02)

• NTM stability LH current profile modification
  (?) at (5,2) _at_ 10T ECCD _at_ 180 GHz, Bo 6.6T

• 80 (90) bootstrap current
• 30 MW LHCD and 5 MW (25 MW capable) ICRF/FW for
  external current drive/heating

• n/nGreenwald 0.9,
• H(y,2) 1.4 (ARIES-AT)
• High field side pellet launch allows fueling to
  core, and ?P/?E 5 (10) allows sufficiently low
  dilution

• No ext plasma rotation source
• Vertical and kink passive stability tungsten
  structures in blanket, feedback coils behind
  shield
• n1 RWM feedback control with coils - close
  coupled

• Tungsten divertors allow high heat flux
• Plasma edge and divertor solution balancing of
  radiating mantle and radiating divertor, with Ar
  impurity

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0-D Power/Particle Balance Identifies Operating
Space 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 MWm-2 with peaking of 2.0
• P(SOL) - Pdiv(rad) lt 28 MW
• Qdiv(rad) lt 8 MWm-2

Generate large database and then screen for
viable points
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FIREs Q 5 AT Operating Space

• Access to higher ?flat/?j decreases at higher ?N,
  higher Bt, and higher Q, since ?flat 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/tCR
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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Steady-State High-b Advanced Tokamak Discharge
on FIRE
0 1 2
3 4
time,(current redistributions)
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q Profile is Steady-State During Flattop, t10 -
41s 3.2 tCR
li(3)0.42
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RD Needed for Advanced Tokamak Burning
Plasma Scaling of energy and particle
confinement needed for projections of performance
and ash accumulation. Benchmark codes using
systematic scans versus density, triangularity,
etc. Continue RWM experiments to test theory
and determine hardware requirements. Determine
feasibility of RWM coils in a burning plasma
environment. Improve understanding of
off-axis LHCD and ECCD including effects of
particle trapping, reverse CD lobe on edge
bootstrap current and Ohkawa CD. Development
of a self-consistent edge-plasma-divertor model
for W divertor targets, and incorporation of this
model into core transport model. Determine
effect of high triangularity and double null on
confinement, b-limits, Elms, and disruptions.
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Concluding Remarks
FIRE is able to access quasi-stationary burning
plasma conditions. In addition, an interesting
steady-state advanced tokamak mode appears to
be feasible on FIRE. There are a number of
high leverage physics RD items to be worked on
for operation in the conventional mode and the
advanced mode. There needs to be an increased
emphasis on physics RD for aggressive advanced
modes. The U.S. Administration has shown an
interest in fusion and has approved joining the
ITER negotiations. Congress has also shown
interest with Authorization bills that support
ITER if it goes ahead, and support FIRE if ITER
does not go ahead. This is consistent with the
consensus in the U.S. fusion community.