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Status and proposals of IEA-LT/ITPA collaboration Multi-machine Experiments

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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Status and proposals of IEA-LT/ITPA collaboration Multi-machine Experiments

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  1. 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 IEA/ITPA meeting Naka Nov. 23, 2003

  2. 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 (r* 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. IEA/ITPA meeting Naka Nov. 23, 2003

  3. 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) IEA/ITPA meeting Naka Nov. 23, 2003

  4. 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 ne, Te, SIon • 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 veff ~ a0.25 • 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. IEA/ITPA meeting Naka Nov. 23, 2003

  5. 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 IEA/ITPA meeting Naka Nov. 23, 2003

  6. 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). IEA/ITPA meeting Naka Nov. 23, 2003

  7. 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) IEA/ITPA meeting Naka Nov. 23, 2003

  8. 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 • ne & Te measurements of the completer profile from pedestal to wall • ne/nsep 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 IEA/ITPA meeting Naka Nov. 23, 2003

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