NSTX-U Collaboration Status and Plans for: ORNL Boundary Physics and RF Research

1. NSTX-U Supported by NSTX-U Collaboration Status and Plans for: ORNL Boundary Physics and RF Research Coll of Wm & Mary Columbia U CompX General Atomics FIU INL Johns Hopkins U LANL LLNL Lodestar MIT Lehigh U Nova Photonics ORNL PPPL Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Illinois U Maryland U Rochester U Tennessee U Tulsa U Washington U Wisconsin X Science LLC Culham Sci Ctr York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAEA Inst for Nucl Res, Kiev Ioffe Inst TRINITI Chonbuk Natl U NFRI KAIST POSTECH Seoul Natl U ASIPP CIEMAT FOM Inst DIFFER ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep J.M. Canik, J.B.O. Caughman, J.-W. Ahn, S.J. Diem, T.K. Gray, D.L. Green, E.F. Jaeger, C.H. Lau, J.D. Lore, A.C. Sontag NSTX-U Collaborator Research Plan Meetings PPPL – LSB B318 April / May 2014

2. Research plans and needs for this year (FY2014) in preparation for NSTX-U operations in FY2015: BP • ORNL Boundary Physics collaboration is organized around three themes • Power and particle exhaust • H-mode pedestal research, with an emphasis on the effects of Li • Effects of 3D fields on edge plasma characteristics • FY14 research includes analysis of existing NSTX data • ELM heat flux footprint measurements and scaling • SOLPS analysis of impact of Li on divertor heat flux • Synergistic work being done to analyze DIII-D detachment • EMC3-EIRENE modeling of impact of 3D fields on detachment • Connects to related modeling of puff-induced asymmetries at C-Mod • …as well as diagnostic preparations • Primary diagnostic is IR cameras (two fast, two 30 Hz systems) • Interfaces with NSTX-U and DAQ need to be finalized • 2nd dual band adapter to be designed and assembled • Two eroding thermocouples installed on inboard, horizontal tile

3. Boundary Physics Research Plans for FY2015-16 • Extend heat flux, q scaling studies to larger parameter space • LSN vs DN using new fast upper-viewing IR camera • Further measurements and modeling of effect of Li on divertor plasma • ELM heat flux/footprint measurements and scaling • Verify cryo physics design and performance • Measure divertor profiles near pump in NSTX-U (instead of project) • Test pumping when cryo available • Neutral pressure measurements using new gauges • Measure impact on global particle control, compare to Li coatings • Experiments and modeling of impact of 3D fields on edge • New experiments measuring impact on pedestal structure and stability, especially at low collisionality (and with NCC?) • Test role of plasma response in heat flux striations/detachment • Pedestal structure (esp. with lithium) • Participate in experiments and analysis of pedestal structure at extended parameter range available in NSTX-U • Extend GK modeling of pedestal to include non-local simulations • Explore access to favorable ELM regimes at reduced collisionality

4. Research plans and needs for this year (FY2014) in preparation for NSTX-U operations in FY2015: RF • The ORNL RF collaboration includes the following research: • Assess HHFW heating and current drive for upgraded plasma conditions, including start-up • Perform experiments related to RF/edge plasma interactions to understand and control RF power flow from the antenna to the core • Provide and operate antenna/edge diagnostics: reflectometer and IR camera • Model and evaluate ECH/EBW scenarios and design power transmission system for 28 GHz long-pulse high-power operation • FY14 activities have focused on diagnostic preparation, operational experience, and modeling of heating scenarios • The design of the ORNL reflectometer has been upgraded and new parts have been ordered • A new IR camera will be tested during long-pulse operation of a two-element antenna array in the PPPL RF test stand • Near-field plasma-edge diagnostics that can be mounted on the antenna array are being discussed • A combination of NBI/RF heating and current drive is being modeled utilizing FASTRAN/ISP and AORSA for long-pulse/steady state scenarios

5. RF Research Plans for FY2015-16 • Assess the performance of HHFW heating and current drive at higher magnetic field and its interaction with NBI-driven H-mode operation • Increased magnetic field strength will move propagation cutoff density and decrease loading: coupling efficiency needs to be determined • Determine changes in core coupling and edge power losses • Second neutral beam and higher field (decreased harmonic mode number) will change interaction with fast ions: simulate and validate losses • Develop HHFW start-up and ramp-up with CHI and NBI • Use HHFW during current ramp-up to bridge the gap between CHI initiation and NBI heating • Provide and operate antenna/edge plasma diagnostics • Install/operate the upgraded reflectometer system to provide plasma density profiles in front of the HHFW array • Install/operate IR camera to monitor temperature distribution on plasma-facing antenna surfaces and RF-induced power deposition in the divertor: couple with array of RF loop and Langmuir probes in divertor • Design and evaluation of ECH/EBW system • Model ECH/EBW heating/current drive/start-up scenarios, including launch angle and polarization • Assist in the design/development of 28 GHz transmission/launching system

6. Ideas to enhance participation in NSTX-U research/program by U.S. Universities, early-career researchers, and students • Allow/encourage off-site collaborators to lead research areas and experiments, not just support them • Perspective from doing this as part of a lab: the ability to do fulfilling research from off-site is entirely dependent on the on-site coordination • Could expand pool of potential collaborators (especially part-time), but they may not have a strong on-site personality protecting them • NSTX was good at this, trick is to stay good with more competition • Create a standardized, transparent allocation of run time in each TSG • Reserved run time (several days?) for university collaborators, students and early-career researchers • In addition to the normally allocated run time for each TSG • Competitively awarded after initial TSG allocation complete • Expected 15 weeks of run time in 2015 (Recent Congressional Budget?) should allow for some flexibility in run time allocation