2014-2018 NSTX Research Plans and Key Diagnostics for Macroscopic Stability

1. NSTX Supported by 2014-2018 NSTX Research Plans and Key Diagnostics for Macroscopic Stability College W&M Colorado Sch Mines Columbia U CompX 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 Illinois 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 Jong-Kyu Park and Jack Berkery for NSTX team Macroscopic Stability Group Meeting B252, PPPL September 23, 2011

2. Major guidance for FY14-18 research goals • Major guidance below was discussed in the first meeting • This is almost maintained with some modifications based on comments, such as • RJB: Need harder and more specific goals and deliverables with highlighting new capabilities such as off-axis beams (q and rotation control) • SAS, RJB: Include cross cutting areas such as ELM stability, fast ion physics, 3D physics • SAS, SPG, RJB: Combine disruption mitigation study with improved disruption control FY2014 FY2015 FY2016 FY2017 FY2018 Main goal Compare NSTX and NSTX-U, identify and exploit new physics in NSTX-U Explore and identify off-axis NBCD, q, and rotation effects on stability and disruption Optimize q and control rotation to improve stability and mitigate disruption Combine q optimization, rotation and β feedback control to maximize performance (FNSF/Pilot projection) Integrate MS control to avoid TM, RWM, ELM instability, disruption, with disruption mitigation protection Combine q optimization, rotation control, βN feedback control, RF application to maximize performance and sustain high beta without macroscopic instability, with controlled ELMs, advanced divertor, and disruption mitigation protection. Avoid unexpected disruptions. Explore performance beyond individual FNSF parameters Global stability Assess βN limit with new q-profile and shaping. Recover and assess RWM physics and control Utilize off-axis NBCD to enlarge (βN ,li). Explore NTV and RWM physics with reduced collisionality and different fast ion populations Utilize q optimization and rotation control to achieve high performance operation in optimal stability window Combine q optimization, rotation control, βN feedback control to maximize performance within stability window, including ELMs Tearing stability Identify n=1 EF and correction. Assess new q-profile and shaping effects on TM Identify n>1 EF and correction. Utilize off-axis NBCD to identify q-profie and qmin effects on LM and TM Identify TM stable operating points, in conjunction with global stability. Explore RF to enlarge stable window Establish TM stable operating scenarios with optimized control. Provide FNSF scaling for EF, LM, TM Disruption avoidance Assess disruption characteristics and mitigation techniques Assess and validate predicted halo currents and quench rates. Develop and identify new MGI effects on mitigations Study effects of high temperature or snowflake divertor operation to MHD. Develop MGI feedback control Couple MGI feedback control to mitigate disruptions in high performance stable scenarios. Provide FNSF disruption scaling

3. FY2014 research goals and key diagnostics • Main goal: Compare, identify, exploit new physics in NSTX-U • Global stability: • Assess the βN limit with the new q, shaping, outer-gaps. Find the highest IN or lowest q95 in a few τE sustained discharges with off-axis NBCD • Recover and compare RWM BP+BR control and state space control. Assess differences in RWM behaviors at fixed βN as a function of beam sources • Tearing stability: • Identify n=1 error field and test optimal corrections • Assess differences of error field and TM thresholds by q-profile or fast ion modifications driven by off-axis NBIs. Compare shaping effects on NTMs • Disruption avoidance: • Assess new disruption characteristics • Apply MGI mitigation techniques. Compare MGI with Private Flux Region (PFR) applications • Key diagnostics: • Magnetic refurbishment, rtMSE, rtMPTS, ME-SXR, thermography, thermocouples, SOLC with magnetic probes, electrodes, sensors, radiation tomography • Comments:

4. FY2015 research goals and key diagnostics • Main goal: Identify off-axis NBCD, q, rotation effects on stability and disruption • Explore NTV physics. Establish 3D coil control for rotations. Implement rotation control scheme • Global stability: • Utilize off-axis NBCD to test and enlarge (βN, li) operating window with strong shaping • Test and validate RWM stabilization physics in reduced collisionality and different fast ion populations. Find variability of RWM feedback control on rotation and strong shaping • Tearing stability: • Identify n>1 error field and test optimal corrections • Utilize off-axis NBCD to vary q-profile and qmin and identify their effects on error field thresholds and TMs. Explore fast ion effects on TMs • Disruption avoidance: • Make assessment of halo currents, current quench rates, and disruption energy loss. Validate upgrade design assumptions in preparation for 2MA operations • Test and optimize MGI techniques by varying positions, plenum size, as well as NBIs • Key diagnostics: • Magnetic refurbishment, rtMSE, rtMPTS, ME-SXR, thermography, thermocouples, SOLC diagnostics, fast CHERS, core X-ray Imaging Spectrometer, interferometer rotation measurement, FIDA • Comments:

5. FY2016 research goals and key diagnostics • Main goal: Optimize q and control rotation to improve stability and mitigate disruption • Extend NTV studies in unexplored regimes. Test and optimize the closed loop control of rotation • Global stability: • Utilize q optimization and rotation control for optimal stability for high βN • Extend RWM passive stabilization studies and establish optimal and multi-mode RWM feedback control with optimized q and rotation to sustain high βN • Tearing stability: • Utilize q optimization and rotation control to identify LM and TM stable operating points in conjunction with global stability • Test and develop RF control of TMs • Disruption avoidance: • Study effects of high temperature divertor and snowflake divertor on MHD • Develop active control for disruption avoidances and MGI feedback control for disruption mitigation • Key diagnostics: • Magnetic refurbishment, rtMSE, rtMPTS, ME-SXR, thermography, thermocouples, SOLC diagnostics, radiation tomography, fast CHERS, core X-ray Imaging Spectrometer, edge rotation diagnostics, visible bremsstrahlung imaging, improved reflectometer system • Comments:

6. FY2017 research goals and key diagnostics • Main goal: Combine q optimization, rotation and β feedback control to maximize performance. Provide FNSF/Pilot projection • Global stability: • Combine q optimization, rotation and β feedback control to sustain long-pulse high β operation, with controlled RWMs and ELMs • Assess global stability for FNSF/Pilot relevant regimes and provide projection • Tearing stability: • Establish TM stable operating scenarios with optimized q, rotation and with controlled RWMs and ELMs • Assess LM and TM threshold for extended regimes and provide relevant scaling for FNSF/Pilot • Disruption avoidance: • Assess disruption precursors and disruptions with various MHD origins, develop each disruption avoidance scenarios • Couple MGI feedback control to disruption avoidance scenarios for protection • Key diagnostics: • Magnetic refurbishment, rtMSE, rtMPTS, ME-SXR, thermography, thermocouples, SOLC diagnostics, radiation tomography, fast CHERS, visible bremsstrahlung imaging, core X-ray Imaging Spectrometer, edge rotation diagnostics, edge imaging of pitch angle, lithium beam Zeeman polarimetry • Comments:

7. FY2018 research goals and key diagnostics • Main goal: Integrate MS control to avoid TM, RWM, ELM instability, disruption, with disruption mitigation protection • Combine q optimization, rotation and β feedback control, RWM, RF control on TMs to maximize performance without any macroscopic instability with controlled ELMs • Combine disruption avoidance scenarios with disruption mitigation protection • Achieve 100% disruption free and MHD free scenarios • Achieve this with advanced divertors • Explore performance beyond individual FSNF parameters • Key diagnostics: • New diamagnetic loop, magnetic refurbishment, rtMSE, rtMPTS, ME-SXR, thermography, thermocouples, SOLC diagnostics, radiation tomography, fast CHERS, visible bremsstrahlung imaging • Comments:

8. Prioritization of key diagnostics