High priority MHD research coordination in preparation for the 2008 FWP D. A. Gates, MHD SFG Leader MHD Science Focus Group Meeting B318 PPPL December 12, 2008 College W&M Colorado Sch Mines Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Maryland U Rochester U Washington U Wisconsin Culham Sci Ctr U St. Andrews York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAEA Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI KBSI KAIST POSTECH ASIPP ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep U Quebec NSTX Supported by

NSTX PPPL MHD Science Focus Group meetingDec. 12, SFG meeting goals “to provide recommendations/input for strengthening PPPL's FWP's for the coming year” Promote discussion that stimulates exchange of ideas Exchange information amongst MHD researchers on the MHD related activities of the laboratory Disseminate important information regarding international burning (ITER/ITPA) plasma research priorities

NSTX PPPL MHD Science Focus Group meetingDec. 12, Focus of 2009 work plan for ITER MHD TG ITER Urgent R&D Needs Disruptions (control, mitigation, loads) – major theme Plasma control –Vertical Stabilization –NTM stabilization –Sawtooth control –RWM control –Error Field control Implementation Joint experiments (MDC 1,2,4,5,8,12-14,15-17) Theory/Modeling Scenario Development }

NSTX PPPL MHD Science Focus Group meetingDec. 12, Joint Experiments Continuing MDC-1 Disruption mitigation by massive gas jets MDC-2 Joint experiments on resistive wall mode physics MDC-3NTM physics (incl. error field effects) Closed (2008) MDC-4 NTM physics - aspect ratio comparison MDC-5 Sawtooth control methods for NTM suppression MDC-8 Current drive prevention/stabilisation of NTMs MDC-12Non-resonant magnetic braking MDC-13Vertical stability physics and performance limits MDC-14 Rotation effects on NTMs (+ remainder of MDC-3) New (proposed) MDC-15 Disruption database development MDC-16 Runaway electron generation, confinement, and loss MDC-17 Physics-based disruption avoidance [MDC-10 and MDC-11 transferred to Energetic Particles group]

NSTX PPPL MHD Science Focus Group meetingDec. 12, Disruptions Electromagnetic loads – vertical & horizontal – due to halo currents, disruptions and VDEs –Improve 2D (DINA, TSC) and 3D halo current models –Extend ITPA disruption database: focus on halo currents Runaway electrons –Diagnostics for generation, confinement, loss –Physics basis for runaway suppression by gas injection, MHD activity, or RMP Requirements for ITER’s disruption mitigation system –Experiments and modeling (NIMROD, SOLPS, …) –Gas injection –Alternate delivery methods such as pellet injection Disruption prevention –ECRH heating of precursor islands –Feedback stabilization of NTMs, RWMs or forced rotation of precursors

NSTX PPPL MHD Science Focus Group meetingDec. 12, Plasma Control Issues - Vertical Stability Safe operation limit:  Z MAX /a > 5% Confirm design of in-vessel coils –Characterize plasma disturbances, e.g. ELMs –Effects of noise, disturbances on ITER controllability limits –Up-gradation of VS1 & VS2 as a backup? –Scaling with parameters other than l i,  … Joint Expt (MDC-13): DIII-D, C-Mod, JET, NSTX –Refine past exptal findings on controllable vertical displacements and compare with model predictions –D Humphreys (DIII-D), I Hutchinson (C-MOD), F Sartori (JET), D Gates (NSTX), W Treutterer (AUG), J Lister (TCV)

NSTX PPPL MHD Science Focus Group meetingDec. 12, Plasma Control Issues - NTM Stabilization Requirements for ECCD detection and stabilization –Determine diagnostic requirements for island detection –Confirm power requirements –Launcher capability for planned operating scenarios Rotation effects –On threshold  N – strong evidence from DIII-D, JET, NSTX –Rotation vs rotation shear, direction of rotation –Theoretical understanding lacking Scaling of NTM limiting  with other parameters Suppression through sawtooth control

NSTX PPPL MHD Science Focus Group meetingDec. 12, RWM Control Requirements for control coils and their power supplies –Current, voltage, frequency, toroidal mode requirements for RWM stabilization using ELM control coils External EFC coils –Effects of noise and plasma disturbances on the control system Relook at RWM stability thresholds and destabilization mechanisms (critical velocity concept may not be adequate) –cross-machine comparison of RWM onsets and related MHD activities that may act as triggers ELMS or fishbones, EWM RWM to kink –Identify possible nonlinear destabilzation mechanism Continue benchmarking of RWM feedback codes RFA expts and validation of theoretical models

NSTX PPPL MHD Science Focus Group meetingDec. 12, Error Field Control Error Field Correction: design of EFC methods –Criteria for EF tolerance in all operating scenarios –EFC methods for ITER: vacuum meas., plasma response Effects of ferromagnetic steel in Test Blanket Modules: design of correction coils –Potential effects of TBM fields on many aspects of operation, including equilibrium reconstruction –Modeling needed to quantify these effects –Simulate TBM fields in existing devices? Non-resonant Magnetic Braking –n=1,2,3 external magnetic perturbations –Validation of neoclassical toroidal viscosity models

NSTX PPPL MHD Science Focus Group meetingDec. 12, Schedule for MHD SFG meeting 1:30 - 1:45 Introduction and ITPA/ITER high priority topics in MHD - Dave Gates (15minutes) 1:45-1:55 Space Physics MHD research at PPPL - Jay Johnson (10 minutes) 1:55 - 2:10 Non-Stellarator MHD Theory - Steve Jardin (15 minutes) 2:10-2:20 MRX related MHD research - Masaaki Yamada (10 minutes) 2:20-2:30 MRI experiment - Mark Nornberg (10 minutes) NSTX MHD research –2:30-2:40 RWM and NTV related research - Steve Sabbagh (10 minutes) –2:40-2:50 Disruptions, NTMs, Error fields, and IPEC - Stefan Gerhardt (10 minutes) –2:50-3:00 Scrape off layer currents on NSTX - Hiro Takahashi (10 minutes) 3:00-3:15 Stellarator related MHD research - Hutch Nielson (15minutes) 3:15-close General discussion about contents of presentation to the research council