Focused Boundary Physics Science Meeting | 8th November 2005

1. Boundary Physics Science Focus Group Meeting Tuesday 8th November 2005 PURPOSE OF MEETING: • Identify high priority BP science issues for 2007 FWP. • Focus on opportunities and new initiatives. • Outcome will be compressed into 7-8 slides for RC meeting 23 November. THEMES: • Fusion landscape changed with advent of ITER. • US has 10% of ITER cost but stakes for domestic program much higher Key opportunities • Fusion research can be seen as a risk management program. • Scaleup in ITER’s BP parameters is much higher than other arsea • Strong BP connections to ITER’s PFC’s material choice (must be resolved early ~ 5 year procurement lead time • ITER-like wall on JET is key opportunity • safety issues (e.g. T retention and dust) that will become more conspicuous with site specific safety assessment. • Tritium removal still unresolved. • Survival of ITER’s Be wall depends on correctly modeling heat and particle flux • PWI diagnostics critical • PPPL can be a bridge helping to PFC community, edge plasma community and edge theory community all focus on understanding real plasmas. (INTEGRATION) • Funding critical… should link ideas to ITPA wherever applicable http://nstx.pppl.gov/DragNDrop/Science_Focus_Group_Meetings/11_08_05_FWP_preparation/

2. ITPA Div/SOL High Priority Research Areas • Understanding the effect of ELMS/disruptions on divertor and first wall structures, • Tritium retention & the processes that determine it, • Improve understanding of SOL plasma interaction with the main chamber • Better prescription of perpendicular transport coefficients and boundary conditions for input to BPX modeling Medium-Term • SOL transport (parallel and drift) • High-Z materials operational experience, • Improve our understanding of processes that determine the core impurity level, • The impact of the simultaneous use of different materials (e.g. tritium retention) Possible Items for Joint Work with other TGs • Disruption physics, heat load on the plate (shielding) and mitigation. • ELMs & understanding pedestal gradient (edge-SOL profile database) • Design divertor diagnostics (measurement and FB control) for BPX experiments • Helium exhaust or transport in ITB plasma • Density limits • Fuelling techniques and performance, influence on edge plasma and wall conditions Diagnostics - BP related High Priority Research Areas • Determination of life-time of plasma facing mirrors used in optical systsems. • Development of measurement requirements for measurements of dust, and assessment of techniques for measurement of dust and erosion.

3. ITER (A = 3.1, R = 6.2 m) CTF (A ~ 1.5, R ~ 1.2 m) Spherical Torus (A ~ 1.5, b0 ~ 1) NSTX Program Addresses Broad Fusion Energy Sciences Missions Through Scientific Investigations • Determine physics principles of ST (very high bT and A ~ 1.5) • Complement lower bT and A ~ 3 experiments in addressing key scientific issues of fusion plasmas • Support preparation for burning plasma research (ITPA, ITER) and benefit from it • Complement ITER by establishing attractive configurations for Component Test Facility (CTF) and Demo

4. What Research Milestones in the SFG Area Should NSTX Consider for FY07-08 to Address Its Missions? FY05 FY06 FY07 FY08 Exp. Run-Weeks: 17 12-14 12-14 5) Boundary Physics: Interface between fusion plasmas and normal temperature surroundings Characterize pedestal and Characterize Li pellet & SOL of low-A, H-mode, evaporator coating effectiveness high P/R plasmas

5. Agenda: Tues 8th 10:30 B318 • Charles: Purpose of meeting (5 mins) • Daren: New Center for Plasma Edge Simulation (5 mins) • Stewart: Opportunities in Edge Turbulence(5 mins) • Vlad: NSTX fueling plans (5 mins) • Jim /Ken: Opportunities at JET (5 mins) • Rajesh: Community input for BPO workshop (5 mins) • Raffi: DIII-D research opportunities forum (15 mins) • Agenda: Tues 15th 10:30 B318 • Dick M.. Opportunities for research on LTX • Henry K Opportunities with Li on NSTX • Rajesh Opportunities for heat and particle transport and ELM research • Vlad: Opportunities in Divertor Physics • Charles: Opportunities to study dust and deposition • Steve Scott: (to be confirmed) Opportunities at C-modOther topics...

6. Center for Plasma Edge Simulation - A SciDAC Fusion Simulation Prototype Center to Develop an Integrated, Predictive Plasma Edge/SOL Simulation Code • Led by C. S. Chang (NYU), D.P. Stotler – PPPL Co-PI • Involving also PPPL, ORNL, Columbia, MIT, U. Colo., CalTech, UC Irvine, Lehigh, GA, UT-K, LBL, Rutgers. • Competitively reviewed & funded by DoE at $2M / year (~$250K to PPPL). • Effectively increases funding base by leveraging off of existing projects & grants: 4 SciDACs, 4 ISICs, + others. • Specific physics objectives: • Pedestal build-up, • L-H transition & power threshold, • ELM stability & cycle. • Directly corresponds to FESAC Priorities Panel activities: • Develop testable pedestal simulation code relevant to ITER, • Develop integrated computational model including pedestal & SOL.

7. CPES – A Synergistic, Collaborative Project Involving Theory, Simulation, Computer Science, Applied Math, & Experiment • Core component: Chang’s existing XGC edge NC kinetic code, • Guiding center particle Hamiltonian dynamics with Monte Carlo atoms, • Simulates pedestal buildup due to neutral ionization, including self-consistent radial potential well (Chang, IAEA, 2004), • Predicted scaling for density pedestal width similar to regression analysis of DIII-D data. • Primary extensions: • Import gyrokinetic & solver routines from turbulence codes GTC & GEM  XGC-ET (Lee, Wang), • Extend M3D two fluid code to edge & use to determine ELM onset & simulate ELM crash, • Combine XGC-ET & M3D in integrated code package (Samtaney), • Replace XGC’s 2-D, single species neutral model with comprehensive module based on DEGAS 2 (Stotler), • Add time-dependence to DEGAS 2’s main tracking routine, • Update atomic physics and plasma-material interaction data (with ORNL). • Develop & implement gyrokinetic equations for steep gradient plasmas (Hahm).

8. CPES is a Prototype FSP - Computer Science / Applied Math Tools Scalable to a Full FSP • Data management: adaptive, automated workflow system, • Code integration & coupling (Samtaney), • Runtime monitoring; interactive & autonomic control (Feibush), • Transparent & ubiquitous data access, • Data analysis & visualization. • Code optimization, • Use of MPP resources (Ethier), • Development of advanced solvers to improve speed, robustness, and accuracy.

9. Opportunities in Edge Turbulence S.J. Zweben, R.J. Maqueda, J.L. Terry, T. Munsat, J.R. Myra, T. Stoltzfus-Dueck, D.P Stotler, C.E. Bush, D. D’Ippolito, O. Grulke, J.A. Krommes, B. LeBlanc, R. Maingi, D.A. Russell, S.A. Sabbagh, A.E. White, K.M. Williams et al PPPL 11/7/05 • NSTX probably has the ‘best’ data on edge turbulence of any tokamak or ST (2-D vs. time, 100’s of shots) Opportunites: • collaborate with other labs (C-Mod, TJ-II, JET, RFX ?) • continue detailed analysis (velocity fields, blob tracks) • collaborate with theorists (PPPL, Lodestar, LLNL) • improve GPI diagnostic (Nova camera, APD array ?) • make time available for dedicated XP’s next year

10. Cause and origin of edge turbulence blobs R. Maqueda 11/7/05 How, why, when do turbulence perturbations in the GPI main emission layer convert into detached, radially moving blobs? • A variety of H-mode behavior is observed with GPI: from quiescent H-modes (no blob activity) to “continuous blobbing” activity. • Nevertheless, blobs in H-modes (between ELMs) are isolated (much less frequent) than during L-modes. • Blobs are also not observed soon after the L-H transition, starting only after some time. With a systematic study of the above observations one may study the cause and origin of the turbulence blobs. • Is there a change in confinement parameters (diffusivity) between “non-blobbing” and “blobbing” H-mode phases? • To what extent H-mode blobs mimic the characteristics of ELMs ...are blobs “m-ELMs”? • Can blobs be used to “diffuse” (some of) the H-mode particle/energy exhaust into the large, outboard PFCs and away from the small divertor region? ...or expand the footprint at the divertor? Are blobs “good” or “bad”?

11. NSTX fueling plan is part of Particle Control section of NSTX 5-year Research Plan • Serves two goals - enabling technology and physics studies • Need for particle control in NSTX plasmas • Enabling technology: develop fueling, pumping, wall conditioning techniques (SGI, CT, pellet injector, divertor cryo-pumps, staged lithium plan, hot and cold boronization, plasma boronization, improved He GDC) • Physics studies: • understand recycling sources in all-carbon machine - molecular processes, MARFE (FY05, FY06) • New promising fueling techniques (SGI, CTI)

12. NSTX fueling plan is part of Particle Control section of NSTX 5-year Research Plan • Serves two goals - enabling technology and physics studies • Need for particle control in NSTX plasmas • Enabling technology: develop fueling, pumping, wall conditioning techniques (SGI, CT, pellet injector, divertor cryo-pumps, staged lithium plan, hot and cold boronization, plasma boronization, improved He GDC) • Physics studies: • understand recycling sources in all-carbon machine - molecular processes, MARFE (FY05, FY06) • New promising fueling techniques (SGI, CT)

13. NSTX fueling plan is part of Particle Control section of NSTX 5-year Research Plan • Serves two goals - enabling technology and physics studies • Need for particle control in NSTX plasmas • Enabling technology: develop fueling, pumping, wall conditioning techniques (SGI, CT, pellet injector, divertor cryo-pumps, staged lithium plan, hot and cold boronization, plasma boronization, improved He GDC) • Physics studies: • understand recycling sources in all-carbon machine - molecular processes, MARFE (FY05, FY06) • New promising fueling techniques (SGI, CTI)

14. Supersonic gas jet fueling is a unique technique studied on NSTX • Implemented in FY04, ran XP in FY05 • NSTX results to date - compatible with H-mode, fueling efficiency 0.1 - 0.3 (to be presented at FY05 Results Review) • Experiments to continue in FY06 with improved SGI (to be presented at FY06 Research Forum) • Expected to be an important tool in lithium experiments • Unique contribution of NSTX to novel fueling system development. Viewed as supplemental approach for ITER • Physics of high pressure gas jet penetration through SOL

15. New Ideas, seemingly highly regarded at JET

16. New Aspects, deserving of technical evaluation

17. Ongoing Collaborations, possibly some new aspects

18. Spectroscopy upgrade for the beryllium wall and tungsten divertor (project under discussion) Requirement to cover routinely from Z=2 (He) and Z=4 (Be) to Z=74 (W) • Visible/UV spectroscopy • Outer divertor line of sight • monitoring W in divertor Several spectroscopy systems to be modified, upgraded or reinstated : • Visible • UV • VUV/XUV • X-ray • Visible spectroscopy • Two divertor viewing periscopes • Two spectrometers for C/Be sources Capability to monitor ‘standard’ impurities will be retained in all cases

19. VUV/XUV spectroscopy • Two spectrometers with scanning mirror system • Upper inner wall/ vertical target plate & lower inner wall/divertor • Diagnoses Be/W/C etc. Several modifications under consideration: • Install new scanning system • Upgrade or replace spectrometers to cover entire wavelength range • New CCD detectors • Reinstate visible channels to allow W/Be source measurements

20. 2005 DIII-D Research Forum • Task Force Structure • ITER foci • ITPA activities • Opportunities for NSTX program • ITER design decisions imminent • 2005 ROF process • Submissions • Participation • Selection • Recent Highlights and new opportunities

21. DIII-D Research Structure http://fusion.gat.com/exp/2005/forum.html

22. Recent Highlights

23. Divertor Detachment with Ar in Hybrid Regime

27. ELMs in the SOL and Boundary

31. Impurity Sources and Transport

37. DiMES

42. New Capabilities • Double Null Pumped Divertor • FW system • FMIT @ 60 MHz, ABB @ 100 MHz: < 3MW available • EC system • 6 CPI gyrotrons • Beam box rotation for counter injection

44. 2005 ROF Process • Solicitation of proposals: submit via WEB by Nov. 14 • Sooner the better for getting on the agenda • Get your proposals in even if you are not going to attend • Forum Nov. 15-17 • Plenary morning session: NSTX contributions overview • Parallel sessions, multiple meeting rooms for remote participation