High-β Steady-State Advanced Tokamak Scenarios for ITER and FIRE

1. FIRE Collaboration http://fire.pppl.gov AES, ANL, Boeing, Columbia U., CTD, GA, GIT, LLNL, INEEL, MIT, ORNL, PPPL, SNL, SRS, UCLA, UCSD, UIIC, UWisc High-b Steady-State Advanced Tokamak Scenarios for ITER and FIRE Dale Meade APS-DPP Annual Meeting Savannah, Georgia November 15, 2004

2. High- Steady-State Advanced Tokamak Regimes for ITER and FIRE D. M. Meade1, N. R. Sauthoff1, C. E. Kessel1, R.V. Budny1, N. Gorelenkov1, G.A. Navratil2, J. Bialek2, M. A. Ulrickson3, T. Rognlein4, J. Mandrekas5, S. C. Jardin1 and J. A. Schmidt1, 1Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA 2Columbia University, New York, NY 10027, USA 3Sandia National Laboratory, Albuquerque, NM 87185, USA 4Lawrence Livermore National Laboratory, Livermore, CA 94551, USA 5Georgia Institute of Technology, Atlanta, GA 30332, USA Abstract. An attractive tokamak-based fusion power plant will require the development of high- steady-state advanced tokamak regimes to produce a high-gain burning plasma with a large fraction of self-driven current and high fusion-power density. Both ITER and FIRE are being designed with the objective to address these issues by exploring and under-standing burning plasma physics both in the conventional H-mode regime, and in advanced tokamak regimes with N ~ 3 - 4, and fbs ~ 50 - 80%. ITER has employed conservative scenarios, as appropriate for its nuclear technology mission, while FIRE has employed more aggressive assumptions aimed at exploring the scenarios envisioned in the ARIES power-plant studies. The main characteristics of the advanced scenarios presently under study for ITER and FIRE are compared with advanced tokamak regimes envisioned for the European Power Plant Conceptual Study (PPCS-C), the US ARIES-RS Power Plant Study and the Japanese Advanced Steady-State Tokamak Reactor (ASSTR). The goal of the present work is to develop advanced tokamak scenarios that would fully exploit the capability of ITER and FIRE. This paper will summarize the status of the work and indicate critical areas where further R&D is needed. The PPPL work was supported by DOE Contract # DE-AC02-76CHO3073.

3. ARIES Economic Studies have Defined the Plasma Requirements for an Attractive Fusion Power Plant Plasma Exhaust Pheat/Rx ~ 100MW/m Helium Pumping Tritium Retention High Gain Q ~ 25 - 50 ntET ~ 6x1021 m-3skeV Pa/Pheat = fa ≈ 90% Plasma Control Fueling Current Drive RWM Stabilization High Power Density Pf/V~ 6 MWm-3 ~10 atm Gn ≈ 4 MWm-2 Steady-State ~ 90% Bootstrap Significant advances are needed in each area. High gain, high power-density and steady-state are the critical issues.

4. Burning Plasma Experiments and Power Plants

5. ARIES-RS (Q = 25) Critical Issue #1- Plasma Energy Confinement: FIRE and ITER Require Modest (2.5 to 5) Extrapolation • Tokamaks have established a solid basis for confinement scaling of the diverted H-Mode. • BtE is the dimensionless metric for confinement time projection • ntET is the dimensional metric for fusion - ntET = bB2tE = bB . BtE • ARIES-RS Power Plants require BtE only slightly larger than FIRE due high b and B.

6. Two Furnaces to Test Fusion Fire (FESAC 2002)

7. Two Furnaces to Test Fusion Fire (FESAC 2002)

8. • ARIES and SSTR/CREST studies have determined requirements for an attractive power plant. KSTAR • Existing experiments, KSTAR, EAST and JT-SC would exp- and high bN region at low field. EAST JT60-SC • ITER would expand region to bN ≈ 3 and fbs ≈ 50% at moderate magnetic field. • FIRE would expand region to bN≈ 4 and fbs ≈ 80% at reactor-like magnetic field. 12 FIRE Would Test bN Limits at Power Plant Magnetic Fields. Modification of JT60-SC Figure

10. Critical Issue #2 - High Power Densities: Requires Significant (x10) Extrapolation in Plasma Pressure FIRE Could Achieve ARIES-like Power Densities

11. Analysis Tools for These Studies 0-D Burning Plasma Systems Code (Kessel) • operating space within physics and engineering constraints TSC-Tokamak Simulation Code (Kessel, Jardin) • free boundary equilibria, transport, current drive, radiation • time evolving coil currents VALEN (Navratil, Bialek) • 3-D finite element electromagnetic code for RWM control modeling • RWM mode structure provided by free boundary DCON stability analysis TRANSP (Budny) • fixed boundary, detailed models for transport, NBCD, ICFW, LHCD • TSC data are input for TRANSP • Calculate energetic particle distribution functions NOVA-K (Gorelenkov) • Global hybrid, kinetic/MHD, eigenvalue perturbative code • Finite orbit width effects for the drive, most important damping mechanisms are included.

13. Recent ITPA Results on Confinement • CDBM (Cordey et al) extended H-mode scaling to a two term (core and pedestal model). IAEA FEC 2002 and Nucl. Fusion43 No 8 (August 2003) 670-674 H(y, 2) 1.0 1.03 1.18 1.25 1.22 1.27 Q 9 10 15 25 22 26 • ITER98(y,2) is pessimistic relative to b scans in DIII-D and JET. A new scaling is being evolving from ITPA CDBM March 8-11 meeting that will reduce adverse b scaling (similar to electrostatic gyro-Bohm model). • Increased pedestal pressure dependence on triangularity (Sugihara-2003).

14. New ITPA Scaling Opens High-Q H-Mode Regime for FIRE • Systematic scans of tE vs b on DIII-D and JET show little degradation with b in contrast to the ITER 98(y, 2) scaling which has tE ~b-0.66 • A new confinement scaling relation developed by ITPA has reduced adverse scaling with b see eq. 10 in IAEA-CN-116/IT/P3-32. Cordey et al. • A route to ignition is now available if high bN regime can be stabilized.

15. New ITPA Scaling Opens High-Q H-Mode Regime for FIRE • Systematic scans of tE vs b on DIII-D and JET show little degradation with b in contrast to the ITER 98(y, 2) scaling which has tE ~ b-0.66 • A new confinement scaling relation developed by ITPA has reduced adverse scaling with b see eq. 10 in IAEA-CN-116/IT/P3-32. Cordey et al. • A route to ignition is now available if high bN regime can be stabilized.

16. FIRE Physics Objectives Burning Plasma Physics (Conventional Inductively Driven H-Mode) Q ~10 as target, higher Q not precluded fa = Pa/Pheat ~ 66% as target, up to 83% @ Q = 25 TAE/EPM stable at nominal point, access to unstable Advanced Toroidal Physics (100% Non-inductively Driven AT-Mode) Q ~ 5 as target, higher Q not precluded fbs = Ibs/Ip ~ 80% as target, ARIES-RS/AT≈90% bN ~ 4.0, n = 1 wall stabilized, RWM feedback Quasi-Stationary Burn Duration (use plasma time scales) Pressure profile evolution and burn control > 20 - 40 tE Alpha ash accumulation/pumping > 4 - 10 tHe Plasma current profile evolution ~ 2 to 5 tskin Divertor pumping and heat removal > 10 - 20 tdivertor First wall heat removal > 1 tfirst-wall

17. 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 - 10, AT) • Burn time ≈ 20s (2 tCR - Hmode) • ≈ 40s (< 5 tCR - AT) • Tokamak Cost = $350M (FY02) • Total Project Cost = $1.2B (FY02) 1,400 tonne LN cooled coils Mission: to attain, explore, understand and optimize magnetically-confined fusion-dominated plasmas

18. FIRE is Based on ARIES-RS Vision • 40% scale model of ARIES-RS plasma • ARIES-like all metal PFCs • Actively cooled W divertor • Be tile FW, cooled between shots • Close fitting conducting structure • ARIES-level toroidal field • LN cooled BeCu/OFHC TF • ARIES-like current drive technology • • FWCD and LHCD (no NBI/ECCD) • • No momentum input • • Site needs comparable to previous • DT tokamaks (TFTR/JET). • • T required/pulse ~ TFTR ≤ 0.3g-T

19. FIRE Plasma Regimes H-ModeAT(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/nG0.7 0.85 1.7-0.85 H(y,2) 1.1 1.2 – 1.7 0.9 - 1.4 bN1.8 ≤ 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 • Hybrid Mode • Two Freq ICRF ITB • Reversed Shear AT - “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.

20. FIRE Conventional H-Mode Operating Range Expanded Nominal operating point • Q =10 • Pf = 150 MW, 5.5 MWm-3 Power handling improved • Pf ~ 300 MW, 10 MWm-3 Physics basis improved (ITPA) • DN enhances tE, bN • DN reduces Elms • Hybrid mode has Q ~ 20 Engineering Design Improved • Pulse repetition rate tripled • divertor & baffle integrated

21. Q = 5 FIRE AT Mode Operating Range Greatly Expanded 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.

22. Integrated Modeling for FIRE Burning Plasmas AE/EP Modes PEST3 Other 3D MHD GTWHIST Impurity transport TRANSP SPRUCE/ICRF NUBEAM CURRAY FP QL, DKE TSC JSOLVER BALMSC PEST2 VALEN ACCOME AORSA WHIST Parks PRL SOL/Divertor Neutrals LSC

23. Modeling FIRE Burning Advanced Tokamak • FIRE Advanced Tokamak • • Free boundary • • Energy and current transport • • Density profile assumed • • Empirical thermal diffusivities • • ICRF/FW from AORSA • • LHCD from LSC/ACCOME • • Bootstrap current, Sauter single ion • • Coronal equilibrium impurities • • Ar introduced to radiate more power • • PF coils and structures • • Control of plasma current, position • and shape t = 12-41 s Ip = 4.5 MA BT = 6.5 T

24. Modeling FIRE Burning Advanced Tokamak Ip = 4.5 MA BT = 6.5 T H-mode edge also simulated

25. “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 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

26. Examining Perturbations of FIRE Burning AT Also examined density perturbations 5 MW perturbation to PLH Flattop time is sufficient to examine CD control t = 12 s t = 25 s t = 25 s t = 41 s

27. Application to ITER is also being studied as part of ITPA.

28. FIRE has Passed DOE Physics Validation Review • The DOE FIRE Physics Validation Review (PVR) was held March 30-31 in Germantown. • The Committee included: S. Prager, (Chair) Univ of Wisc, Earl Marmar, MIT, N. Sauthoff PPPL, F. Najmabadi, UCSD, Jerry Navratil, Columbia (unable to attend), John Menard PPPL, R. Boivin GA, P.  Mioduszewski ORNL, Michael Bell, PPPL, S. Parker Univ of Co, C. Petty GA, P. Bonoli MIT, B. Breizman Texas, • PVR Committee Consensus Report: • The FIRE team is on track for completing the pre-conceptual design within FY 04. FIRE would then be ready to launch the conceptual design. The product of the FIRE work, and their contributions to and leadership within the overall burning plasma effort, is stellar. • Is the proposed physical device sufficiently capable and flexible to answer the critical burning plasma science issues proposed above? • The 2002 Snowmass study also provided a strong affirmative answer to this question. Since the Snowmass meeting the evolution of the FIRE design has only strengthened ability of FIRE to contribute to burning plasma science.

29. Next Step Option Activities • FIRE • • FIRE Physics Validation Review successfully passed . March 30-31, 2004 • • FIRE Pre-Conceptual Activities are completed. September 30, 2004 • • Ready to begin Conceptual Design Activities. Now • • “Hold our FIRE” as per Fusion Energy Sciences Advisory Committee • recommendation • ITER AT • • Extend performance of ITER using Advanced Tokamak operation • • Fully exploit the capability of ITER (increase power to ~1GW at steady-state) • • Recover original ITER capability for nuclear testing • • Would address several physics tasks requested by IT Leader

30. Current Profiles for FIRE and ITER “AT” Modes FIRE 100 % non-inductive and quasi-stationary ITER 97 % non-inductive and quasi-stationary Desired AT profiles achieved for FIRE • q > 2.5 everywhere • qmin = 2.7 @ r/a ≈ 0.8 • above has L-Mode edge, also have H-mode edge case- little change • Desired AT profiles not yet achieved for ITER • • q > 1.9 everywhere, some residual ohmic • • rising q, working on flattening and reversal • • qmin @ r/a ≈ 0.8 • • optimization of startup and NINB/ICFW mix • iterating with TRANSP source info • working on H-mode edge case

31. Optimize CD mix & startup to flatten q profile First Results from ITER-AT Studies Using TSC,TRANSP and NOVA-K Goal is Steady-State, bN ≈ 3.5, fbs > 60% fbs , Q > 5 using NINB, ICFW and LHCD First case has bN ≈ 2.5, fbs ≈ 44%, ≈ 97% non-inductive and Q ≈ 5.

32. Applying FIRE-Like RWM Feedback Coils to ITER Increases b-limit for n = 1 from bN = 2.5 to 4.9 G. Navratil, J. Bialek VALEN Analysis Columbia University ITER PF Coils No-wall limit RWM Coils in every third port Baseline RWM coils located outside TF coils FIRE-like RWM coils would have large stabilizing effect on n=1 • Engineering feasibility of internal control coils needs to be determined

33. ITER and FIRE AT Scenarios Can be Extended ARIES-AT (bN = 5.4, fbs = 90%) Goals: 2X ITER power level to 1000 MW and 2X FIRE Pulse Length

34. TAE Modes in FIRE AT Regime Nova-K: N. Gorelenkov • ba(0) = 0.62%, Rba = 3.34 %, T(0) = 14 keV • n = 6 - 8 unstable • radially localized just inside qmin @r/a = 0.8 • modes are weakly unstable due to low alpha-particle beta

35. TAE Modes in ITER Hybrid Regime Nova-K: N. Gorelenkov • ba= 2.1%, Rba =15.5 %, Te(0) = 34 keV • n = 3 - 11 unstable (only odd modes have been studied). • radially localized near r/a = 0.5 • TAEs are strongly driven with beam ions as much as alphas (H.Berk talk)• strong drive is due to high ba as a result of high ion temperature • Perturbative approach may not be valid. • Strong particle transport is expected (H.Berk talk).

36. Both ITER and FIRE are Proposing to Explore and Exploit Advanced Tokamak Operating Modes

37. ITER and FIRE Advanced Tokamak Operating Modes Pose Challenges for Plasma Technology

38. 25 MW/m2

39. Exhaust: Type II ELMs occur with strong shaping • database extended down to q95  3.5 • closeness to DN necessary: type II obtained in whole d-range • accessible when DXp  0.02 m (0.35  d  0.5) • stability analysis: edge shear stabilises lower n, squeezes eigenfunction Zohm IAEA 2002

40. Pure Type-II ELMy phases achieved at high bpol in the QDN configuration • Type-II ELMs may be accessible at higher Ip with higher power: to be done • Not seen with lower single-null configuration at high pol: QDN configuration may be necessary (although jedge was also different) Type-II ELMs in “JT-60U high-βpol” scheme bpol.= Da 1.5 MA 1.2 Da 1.5 MA 1.3 1.35 MA • ELMs get smaller with increasing pol and frequency/irregularity increases • Te,ped and ne,ped remain high at high bpol: not consistent with Type-III ELMs Da 1.5 1.2 MA Da 1.6 1.2 MA Da 1.8 1.2 Te ped.(keV) 0.9 3.6 ne pedl, (x1019m-2) 2 Time (s) 19.60 19.65 19.75 Presentation to STAC Jerome Pamela EFDA-CSU, 05 March 2004

41. Note: ITER and FIRE first wall (Be to VV) cost/PFC area ≈ equal at $0.25M/m2

45. Status and Plans for FIRE • FIRE has made significant progress in increasing physics and engineering capability since the Snowmass/FESAC recommendations of 2002. • FIRE successfully passed the DOE Physics Validation Review (PVR) in March 2004. “The FIRE team is on track for completing the pre-conceptual design within FY 04. They will then be ready to launch the conceptual design. The product of their work, and their contributions to and leadership within the overall burning plasma effort, is stellar.” - PVR Panel • Most of the FIRE resources were transferred to US - ITER activities in late 2003. The resources remaining in 2005 will focus on development of advanced capabilities for ITER - e.g., integrated AT modes, high power PFCs. • The present US plan assumes that a decision to construct ITER is imminent. If an agreement on ITER is not attained, FIRE is ready, to be put forward as recommended by FESAC.

46. Concluding Remarks • FIRE Pre-Conceptual Design has been completed - exceeding original goals. • Steady-state FIRE AT mode using FWCD and LHCD has fbs ≈ 77% and is 100% non-inductive. High bN(~4) with close coupled RWM stabilization would produce power-plant-level fusion-power densities of 5 MWm-3 for 4 tCR. • FIRE has passed DOE PVR and is ready to be put forward as an attractive burning plasma experiment if the six-party ITER negotiations breakdown. • Transition of NSO activities to supporting the “option” of extending ITER performance using AT operation has been accomplished without missing a step. The goal is to recover most of the capability of the original ITER. • Initial ITER-AT studies successfully at producing steady-state scenario using FWCD and LHCD with fbs ≈ 48% and 97% non-inductive current drive. Studies are continuing to optimize the current drive, and to increase bN from 2.5 to 3.5. • Close coupled RWM coils proposed by FIRE are expected to provide n = 1 stability up to bN = 4.2 in FIRE and 4.9 in ITER. • TAE instability studies indicate that AT modes in both ITER and FIRE will have multiple unstable modes, with NINB ions being a significant drive term in ITER.

47. Recent News • Recent six-party Vice Ministers meeting (P4) on November 8-9 failed to arrive at an agreement on the construction site for ITER. • Europe continues discussions “to go it alone.” • a new negotiating mandate is expected to be proposed next week by the European Commission, the EU's executive arm.The new mandate, to be unveiled on Tuesday (Nov 16, will "give priority to a solution involving all six parties, but there is a fallback option which is to do it with less than six," said one EU source. (AFP-Agency French Press-Nov 12, 2004) • EU ministers for science and research will debate the commission's recommendations at their next meeting on November 26. • US continues to move forward. DOE budget proposals for FY 2006 are now before the OMB. These budgets should contain a budget increase for ITER construction. They must be finalized by ~ late December to be included in the President’s FY 2006 budget in early February. Bottom Line - we will know by end of December. We should be ready.