Proposed FY10 heat transport Joule milstone

1. Proposed FY10 heat transport Joule milstone Tentative wording from Dave Hill (conservative - doesn’t over-promise) • SOL thermal transport physics: Build a database from C-Mod, NSTX, and DIII-D comparing lambda_q and peak heat flux vs. SOL parameters such as PSOL, q||, and flux expansion. All three machines have heat flux measurements. Dedicated run time, analysis, and reporting is necessary to build such a database, as was the case of the confinement database now in place. Such a database would be helpful for ITER and might motivate an international activity. • “One issue that needs to be resolved is the balance of effort going into studies of edge "transport" (i.e., fluctuations) vs. building a database of midplane and divertor parameters.” (Dave Hill and Rich Hawryluk favor a more focused effort)  1

2. Proposed FY10 heat transport Joule milstone • Issue: prediction of power handling challenge for next step devices (FDF, NHTX, CTF…) depends on heat flux footprint • Empirical scalings from uncontrolled databases thought to be unreliable • Simple analytic scalings (from classical parallel transport and variety of cross-field transport aka Connor 1998) not trusted? • Goal: measure divertor lqdiv in C-Mod, DIII-D and NSTX, and use mapping to get lqmid to create controlled, dedicated database • Use same measurement techniques - IRTV/probes • Use same strategy to locate separatrix • Similar discharges or at least scaled poloidal shapes? • Major scans: Ip, Bt, Paux, drsep (d, k, X-point height?) • Need some though on ELM regime/impact of ELMs • Diagnostics needed: IR cameras with up/down view, divertor Langmuir probes, divertor bolometry, midplane ne/Te for separatrix location 2

3. Proposed FY10 heat transport Joule milstone • Issues for measurement in NSTX • Impact of Lithium on IR measurements • It’s probable that Lithium is burned away from high heat flux strike point, but this needs verification • Consider acceleration of a 2-color IR camera system • New fast IR camera (up to 10 kHz) being implemented for NSTX • Camera in house, with bench calibrations in progress • 2-12 mm range -> possible 2-color measurement with filters • Alternately, can do experiments before Lithium put into vessel (however we probably want to understand the impact of Lithium on these widths!) • Is Thomson data too coarse for separatrix location? Does this require the additional Thomson channels promised beginning in FY10? (too much power for plunging probe) • The high resolution edge SXR system (JHU) would be very valuable for upstream profiles - can it be accelerated enough? • Should we try to connect to SOL turbulence and theory independent of the promises made in the milestone? 3

4. Backup 4

5. 14 FY07 08 09 10 11 12 13 Boundary physics program time line FY09-FY13 5 year Optimize Liquid Li interactions Core fueling with CTs Characterize Liquid Li effects Hydrogen retention in liquid Li Optimized gas injector fueling Lithium Liquid Li with high input power Core fueling with pellets Midplane and divertor turbulence at higher PNBI Divertor turbulence with X-point probe Upgraded biasing for SOL control Midplane and divertor turbulence comp. with models Scaling of midplane widths Edge biasing for SOL control T & T 2-D divertor physics: new data and model comparison Closed divertor or X-divertor? Detachment at higher PNBI Private flux region studies MARFE models Divertor power accounting Improved detachment control MARFE studies Divertor Pedestal & ELMs High m,n RMP studies Triggering of edge barriers ELM stability, small ELMs EPH modes, RMP effects Model comparison RMP effects on heat flux profile Long pulse small ELM regimes Extend EPH modes Upgraded LLD or cryopump Liquid lithium divertor module Divertor PFC long pulse upgrade Second NBI SGI and center stack gas injector upgrades D2 Pellet injector, Compact Toroid Injector Non-axisymmetric Control Coils SWIFT ion flow + upgraded Penning gauge for particle balance Tools More edge TS chans ERD upgrade X-point probe Edge SXR Divertor imaging spectrometer Fast IR camera Divertor bolometry Divertor Thomson Divertor SXR 5

6. PDD zone Divertor physics and detachment physics program needed for NHTX and ST-CTF design • ST effects: low l||, small R, large outboard side surface area make outer detachment difficult • Power management through flux expansion and detachment may be required for heat dissipation in high power ST’s • ST effects above allow broader test of detachment physics in 2-D codes • Heat flux management through plasma shaping and detachment shows promise in NSTX 1 MA, 6 MW NBI, d=0.6 LSN Reference (125280) PDD (125279) t=0.663 sec CHI gap 6

7. Model DO (Counsell 1999) Edge T & T studies will focus on connection between measured turbulence characteristics and SOL widths PAC21-18 • Motivated by the high divertor and first-wall heat loads in NHTX, ST-CTF, and ITER • Peak heat flux in NSTX > 10 MW/m2 (NHTX qpeak ~ 40 MW/m2) • Dependence of heat flux width (qmid) not well understood in tokamaks • qmid larger in NSTX than high aspect ratio tokamak analytic scalings • Strong IP dependence of NSTX qmid, but magnitude at high Ip overlaps with tokamak database • Turbulence modeling already connecting to analytic theory of blob formation • Recent capability to measure X-point turbulence for correlation w/midplane Maingi EPS06 Lower divertor Midplane GPI Image intensity (a.u.) 124819 Time (s) Maqueda 7