Advanced Tokamak Scenarios for FIRE and Alcator C-Mod

Advanced Tokamak Scenarios for FIRE and Alcator C-Mod Charles Kessel and Dale Meade ITPA Steady-State Energetic-Particle Task Group Meeting St. Petersburg, Russia July 15, 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,

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 ≈ 20 s (2 CR-Hmode) ≈ 40 s (< 5 CR-AT) • Tokamak Cost = $350 M (FY 02) • Total Project Cost = $1. 2 B (FY 02) 1, 400 tonne Mission: to attain, explore, understand optimize magnetically-confined fusion-dominated plasmas

Characteristics of FIRE • 40% scale of ARIES plasma xsection • kx = 2. 0, dx = 0. 7, ripple ≈ 0. 3% • All metal PFCs • Actively cooled W divertor • Be tile FW, cooled between shots • T inventory ~ TFTR • Close Fitting Copper Stabilizers • Position control coils btwn VV shells • RWM coils in the first wall • 75 -115 MHz ICRF for heating and onaxis CB, ~5 GHz LH for off-axis CD, 170 GHz ECCD for NTM stabilization

How Hard should the AT be Pushed? • Reactor studies ARIES and SSTR/CREST have determined requirements for a reactor. • Existing experiments, KSTAR and JT-SC would expand high N region at low field. • ITER would expand region to N ≈ 3 and fbs ≈ 50% at moderate magnetic field. • FIRE would expand region to N≈ 4 and fbs ≈ 80% at reactor-like magnetic field. 12

FIRE Parameters Approach ARIES-RS

FIRE Plasma Regimes H-Mode Operating Modes AT(ss) ARIES-RS/AT • Elmy H-Mode R/a 3. 6 4 • Improved H-Mode B (T) 10 6. 5 8 -6 Ip (MA) 7. 7 5 12. 3 -11. 3 n/n. G 0. 7 0. 85 1. 7 -0. 85 - OH assisted H(y, 2) 1. 1 1. 2 – 1. 7 0. 9 - 1. 4 - “steady-state” (100% NI) N 1. 8 ≤ 4. 2 4. 8 - 5. 4 fbs , % 25 77 88 - 91 Burn/ CR 2 3 -5 steady • Reversed Shear AT • H-mode facilitated by dx= 0. 7, kx = 2, n/n. G= 0. 7, DN reduction of Elms. • AT mode facilitated by strong shaping, close fitting wall and RWM coils.

Simulation of a Standard H-mode in FIRE - TSC • CTM ≈ GLF 23(RN) • m = 1 sawtooth Model - Jardin etal • other effects to be added - Jardin FIRE, the Movie

0 -D Power/Particle Balance Identifies Operating Space for FIRE - AT • Heating/CD Powers – ICRF/FW, ≤ 30 MW – LHCD, ≤ 30 MW • Q=5 • Constraints: – flattop/ CR determined by VV • 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 – P(LH) and P(FW) ≤ max installed powers • I(FW)=0. 2 MA – P(LH) + P(FW) ≤ Paux • I(LH)=Ip(1 -fbs) • Scanning Bt, q 95, n(0)/, T(0)/, n/n. Gr, N, f. Be, f. Ar nuclear heat (4875 MW-s) or TF coil (20 s at 10 T, 50 s at 6. 5 T) – 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

FIRE’s Q = 5 AT Operating Space 1. 0 1. 2 1. 4 1. 6 1. 8 2. 0 1. 2 1. 4 1. 6 1. 8 • 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 2. 0

FIRE’s AT Operating Space Q = 5 - 10 accessible N = 2. 5 - 4. 5 accessible fbs = 50 - 90+ accessible flat/ CR = 1 - 5 accessible If we can access…. . H 98(y, 2) = 1. 2 - 2. 0 Pdiv(rad) = 0. 5 - 1. 0 P(SOL) Zeff = 1. 5 - 2. 3 n/n. Gr = 0. 6 - 1. 0 n(0)/ = 1. 5 - 2. 0

“Steady-State” High- Advanced Tokamak Discharge on FIRE 0 1 2 3 4 time, (current redistributions)

q Profile is Steady-State During Flattop, t=10 - 41 s ~ 3. 2 CR Profile Overlaid every 2 s 0 10 20 30 40 , s 0 0 10 20 30 2 3 4 5 6 7 40 , s 0 0 1 40 li(3)=0. 42 10 20 30 40

Tests of Self- Organization before DT Transport Self-heating (90%) Bootstrap (90%) • An advanced reactor plasma must be largely self-organized with minimal external control. • We shouldn’t wait until first DT on a BPX (~2015 -2018) to determine the conditions for a tokamak to self-organize, and an access path. • There is ~ 15 years for: - a focused effort on an experimental simulation (Paux = C n 2 T 2) - a comprehensive computer simulation of an advanced BP

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. Develop techniques for NTM stabilization in H-Mode (10 T) and AT(6. 5 T). • 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. • Continued development of integrated simulations and integrated experiments is needed. A self-organization experiment would be an important result.

Latest News about US Fusion Funding House of Representatives Energy and Water SC Appropriations - July 9, 03 "The Committee recommendation for fusion energy sciences is $268, 110, 000, an increase of $10, 800, 000 over the budget request. The Committee is cautiously supportive of the Administration's proposal to re-engage in the International Thermonuclear Experimental Reactor (ITER) project, but is disappointed that the budget request provides $12, 000 in funding for the U. S. ITER effort only at the expense of displacing ongoing domestic fusion research. The additional $10, 800, 000 includes $4, 000 for burning plasma experiments, including support for ITER and for the domestic FIRE project, $5, 200, 000 for fusion technology, and $1, 600, 000 for advanced design and analysis work. If the Department intends to recommend ITER participation in the fiscal year 2005 budget request, the Committee expects the Department will so so without harm to domestic fusion research or to other programs in the DOE Science budget. "