Advanced Tokamak Regimes in the

Fusion Ignition Research Experiment (FIRE)

30th Conference on Controlled Fusion and Plasma PhysicsSt. 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 http://fire.pppl.gov

Dale Meadefor 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 GainQ ~ 25 - 50

nET ~ 6x1021 m-3skeVP/Pheat = f ≈ 90%

Steady-State~ 90% Bootstrap

ARIES Economic Studies have Defined Requirements for an Attractive Fusion Power Plant

Plasma ExhaustPheat/Rx ~ 100MW/m

Helium PumpingTritium Retention

Plasma ControlFueling

Current DriveRWM Stabilization

Significant advances (> 10) are needed in each area. In addition, the plasma phenomena are non-linearly coupled.

Present Data

Region

CREST

ARIES-AT

ARIES-RSASSTR

SSTR

Steady StateReactor

Designs

Bt(T)2 4 6 8 10 11

6

5

4

3

2

1

00

βN

• Reactor studies ARIES and SSTR/CREST have determined

requirements for a reactor.

ITER

AT

H

• ITER would expand region toβN ≈ 3 and fbs ≈ 50% at moderate magnetic field.

FIRE

AT

H

• FIRE would expand region to βN≈ 4 and fbs ≈ 80% at reactor-like magnetic field.

• Existing experiments, KSTAR and JT-SC would expand high βN region at low field.

KSTARJT60-SC

Attractive Reactor Regime is a Big Step From Today

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 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-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

βN 1.8 ≤ 4.2 4.8 - 5.4

fbs ,% 25 77 88 - 91

Burn/CR 2 3 - 5 steady

• H-mode facilitated by x= 0.7, x = 2, n/nG= 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 (5,2) @ 10T ECCD @ 180 GHz, Bo = 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/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

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/a=0 and r/a=0.75

• I(FW)=0.2 MA

• I(LH)=Ip(1-fbs)

• Scanning Bt, q95, n(0)/<n>, T(0)/<T>, n/nGr, βN, fBe, fAr

• 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) ≤ Paux

– Q(first wall) < 1.0 MWm-2 with peaking of 2.0

– P(SOL) - Pdiv(rad) < 28 MW

– Qdiv(rad) < 8 MWm-2

Generate large database and then screen for viable points

1.0 1.2 1.4 1.6 1.8 2.01.0 1.2 1.4 1.6 1.8 2.0

FIRE’s Q = 5 AT Operating Space

• Access to higher flat/j decreases at higher βN, 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

FIRE’s AT Operating SpaceQ = 5 - 10 accessible

βN = 2.5 - 4.5 accessible

fbs = 50 - 90+ accessible

flat/CR = 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)/<n> = 1.5 - 2.0

“Steady-State” High-β Advanced Tokamak Discharge on FIRE

0 1 2 3 4

time,(current redistributions)

q Profile is Steady-State During Flattop, t=10 - 41s ~ 3.2 CR

0 10 20 30 40 , s

0 10 20 30 40 , s

0 10 20 30 40

0 10 20 30 40

li(3)=0.42

0 1 2 3 4 5 6 7

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, β-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