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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 Status and proposals of IEA-LT/ITPA collaboration Multi-machine Experiments Presented by N. Asakura, ITPA SOL and Divertor physics topical group and Collaborators The Second IEA Large Tokamak Workshop, Naka, 23-24, Nov. 2003 Contents: Report on DSOL#1-6 and one new proposal
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-1: Scaling of Type-1 ELM energy loss Goal: To better predict divertor and first-wall heat loads during ELMs Areas of concentration ELM divertor heat pulse profile, deposition time and amount Processes whereby core heat/particles are transferred to SOL Characterization of radial transport of ELM energy Collaborators: A. Loarte, T. Leonard, N. Asakura, W. Suttrop, G. Counsell, A. Herrmann Results (2003) JET/Fundamenski measurement of ELM radial velocity/energy falloff ASDEX Upgrade measurement of far SOL ELM m/n number JET - DIII-D dimensionless comparison ( * scaling)& AUG (in pedestal group) Plans (2004) Continued measurement and analysis of radial ELM propagation (radial velocity and particle flux at the first wall/in SOL): MAST, AUG, DIII-D, JT-60U, JET Joint. Exp. Plan: Toroidal and Poloidal distributions of heat flux(AUG:Feb. and MAST:June) ELM heat and particle measurements may be available in joint experiment plans in pedestal group.
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-2: Tritium codeposition Goal: To better predict the T inventory Areas of concentration Understanding of local and global carbon transport Understanding of chemical sputtering yield variation among experiments Development and sharing of new diagnostics (e.g. quartz microbalance) Effect of mixed materials on T inventory (e.g. W or Mo) Collaborators: V. Philipps, D. Whyte, G. Federici, P. Coad, P. Ghendrih, V. Rohde, B. Lipschultz, S. Higashijima Results (2003) Achievement of global balances of material erosion and deposition (JET, AUG, TEXTOR) Divertor geometry (strike point location) affects co-deposition (demonstration of QMB in JET) Plans (2004) C-13 injection experiments to understand C migration (DIII-D, JET,JT-60U, TEXTOR), and also global transport (see DSOL-6) Hydrocarbon injection to quantify chemical erosion data (JET, AUG, TEXTOR, JT-60U)
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-3: Scaling of radial transport Goal: To better predict divertor & first-wall power/particle loadings Areas of concentration Develop same measurements techniques for SOL profiles of n e, T e, S Ion Collection of dimensionless similar and dissimilar discharges for analysis Comparison of inner and outer SOL transport and turbulence Collaborators: B. Lipschultz, D. Whyte, G. Matthews, R. Pitts, G. Counsell, A. Kallenbach, T. Nakano, N.Asakura Results (2003) Obtained dimensionless similar (to C-Mod, DIII-D) discharges on JET Effective convective velocity v eff ~ a 0.25 Plans (2004) Multi-machine modeling with fluid code under planning/negiciating (Ped. TG) Expand database from L-mode to H-mode discharges on same tokamaks: Joint Exp. Plan expand database to AUG, NSTX, MAST H-modes.
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-4: Disruptions and effect on materials choices Goals: Better characterize divertor/first-wall heat loading Understand if there are any size effects on the division of power loadings Evaluate the performance of different materials for divertor/first-wall Areas of concentration Comparison of heat deposition time and profile, radiation during thermal quench in multi-machines (over various disruptions: beta-limit, high-density, Locked-mode, etc.). Collaborators: D. Whyte, G. Matthews, R. Pitts, A. Mahdavi, A. Herrmann, R. Granetz, G.Counsell, V. Riccardo, K.H. Finken Results (2003) Broad power deposition profile in the divertor in AUG and JET Power fraction to divertor: different in JET rather than ASDEX-Upgrade/DIII-D Analysis of the effect of disruption mitigation on wall materials Plans (2004) Continued modelling of how the use of different gases affects the power deposition and thus melting Disruption mitigation experiments on JET and C-Mod Comparison of disruptions in ‘similar’ discharges on JET/AUG/DIII-D/MAST
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-5: Role of Lyman absorption in the divertor Goals: Understand whether Lyman absorption is important to include in fluid models Areas of concentration Develop EIRENE to handle radiation transport Benchmark against C-Mod (opacity due to high density) and JET (opacity due to large size) Collaborators: D. Reiter, J. Terry, G. Matthews Results (2003) Implemented pressure (Stark-) broadening Tested against HID lamps - Stark effect small for ITER Plans (2004) Implement isotope effects (line mixing) and and Zeeman splitting Model radiation transfer in JET and C-Mod (existing data).
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 DSOL-6: Parallel transport in the SOL Goal: Capability to predict flow pattern in SOL Areas of concentration SOL flows at a number of points (High-&Low-Field-sides, Top, Divertor): Determination of the flow pattern consistent with experiments and simulations? Determination of influence of the SOL flow pattern on impurity transport Experiments to determine influence of plasma rotation on parallel flows Collaborators: N. Asakura, G. Porter, K. Erents, B. LaBombard, J. Neuhauser Results (2003) HFS SOL Mach flow meas. (C-Mod) - large flows to HFS divertor (also in JT-60U) Doppler measurements (C-Mod, several locations) being compared to Mach probes Puff & Pump affects the SOL flow and particle flux at HFS more than LFS (JT-60U) Plans (2004) Continued Mach probe/Doppler comparisons (C-MOD) Comparison with Experiments and Simulations with drifts, and Influence of the SOL flow (fast flow/ flow reversal) on the impurity transport/shielding is also determined (JT-60U, DIII-D, JET, C-MOD/ UEDGE-code). C-13 injection of global impurity transport (DIII-D, JET, JT-60U, ASDEX-U)
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Divertor/SOL contribution IEA/ITPA meeting Naka Nov. 23, 2003 New proposal - Multi-machine study on separatrix density and edge density profiles Goal: Proper prediction of the separatrix density and its gradient important for controlling particle exhaust and fueling in H-mode Areas of concentration n e & T e measurements of the completer profile from pedestal to wall n e /n sep and fraction of the pedestal inside separatrix Collaborators: A. Kallenbach, G. Porter, K. Erents, D. Mossessian, N. Asakura, G. Counsell Status (2003) Data collected from AUG, C-Mod, DIII-D, JET, JT-60U and MAST Scalings obtained (will be presented in 2004 PSI). Plans (2004) Comparison of data with DIII-D neutral model of pedestal Scalings of density gradients
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