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

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 R&D Concluding Remarks

High Power Density ~ 6 MW -3 ~10 atm High Power Gain Q ~ n  E T ~ 6x10 21 m -3 skeV P  /P heat = f  ≈ 90% Steady-State ~ 90% Bootstrap ARIES Economic Studies have Defined Requirements for an Attractive Fusion Power Plant Plasma Exhaust P heat /R x ~ 100MW/m Helium Pumping Tritium Retention Plasma Control Fueling Current Drive RWM Stabilization Significant advances (> 10) are needed in each area. In addition, the plasma phenomena are non-linearly coupled.

Reactor studies ARIES and SSTR/CREST have determined requirements for a reactor. ITER would expand region  to  N ≈ 3 and f bs ≈ 50% at moderate magnetic field. FIRE would expand region to  N ≈ 4 and f bs ≈ 80% at reactor-like magnetic field. Existing experiments, KSTAR and JT-SC would expand high  N region at low field. Attractive Reactor Regime is a Big Step From Today

Fusion Ignition Research Experiment (FIRE) R = 2.14 m, a = m B = 10 T, (~ 6.5 T, AT) I p = 7.7 MA, (~ 5 MA, AT) P ICRF = 20 MW P LHCD ≤ 30 MW (Upgrade) P fusion ~ 150 MW Q ≈ 10, (5, AT) Burn time ≈ 20s (2  CR -Hmode) ≈ 40s (< 5  CR -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

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.

FIRE Plasma Regimes Operating Modes Elmy H-Mode Improved H-Mode Reversed Shear AT - OH assisted - “steady-state” (100% NI) H-ModeAT(ss)ARIES-RS/AT R/a B (T) I p (MA) n/n G H(y,2) –  N 1.8≤ f bs,% Burn/  CR steady H-mode facilitated by  x = 0.7,  x = 2, n/n G = 0.7, DN reduction of Elms. AT mode facilitated by strong shaping, close fitting wall and RWM coils.

FIRE Plasma Systems are Similar to ARIES-AT  x = 2.0,  x = 0.7 Double null divertor Very low ripple 0.3% (0.02%) NTM stability: LH current profile modification (  ’) at 10T 180 GHz, B o = 6.6T No ext plasma rotation source Vertical and kink passive stability: tungsten structures in blanket, feedback coils behind shield n=1 RWM feedback control with coils - close coupled 80 (90%) bootstrap current 30 MW LHCD and 5 MW (25 MW capable) ICRF/FW for external current drive/heating Tungsten divertors allow high heat flux Plasma edge and divertor solution: balancing of radiating mantle and radiating divertor, with Ar impurity n/n Greenwald ≈ 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

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-m 2 –  (LH)=0.16 A/W-m 2 P(FW) and P(LH) determined at r/a=0 and r/a=0.75 I(FW)=0.2 MA I(LH)=I p (1-f bs ) Scanning B t, q 95, n(0)/, T(0)/, n/n Gr,  N, f Be, f Ar Q=5 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) ≤ P aux –Q(first wall) < 1.0 MWm -2 with peaking of 2.0 –P(SOL) - P div (rad) < 28 MW –Q div (rad) < 8 MWm -2 Generate large database and then screen for viable points

FIRE’s Q = 5 AT Operating Space Access to higher  flat /  j decreases at higher  N, higher B t, and higher Q, since  flat is set by VV nuclear heating Access to higher radiated power fractions in the divertor enlarges operating space significantly

FIRE’s AT Operating Space Q = accessible  N = accessible f bs = accessible  flat /  CR = accessible If we can access….. H98(y,2) = P div (rad) = P(SOL) Z eff = n/n Gr = n(0)/ =

“Steady-State” High-  Advanced Tokamak Discharge on FIRE time,(current redistributions)

q Profile is Steady-State During Flattop, t= s ~ 3.2  CR , s i (3)= Profile Overlaid every 5 s

R&D 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,  -limits, Elms, and disruptions.

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 R&D items to be worked on for operation in the conventional mode and the advanced mode. There needs to be an increased emphasis on physics R&D 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. Concluding Remarks