ITPA – CDBM H-mode threshold database Threshold database status October 2007 - Naka

1. ITPA – CDBMH-mode threshold databaseThreshold database statusOctober 2007 - Naka Yves Martin Centre de Recherches en Physique des Plasmas Association Euratom - Confédération Suisse Ecole Polytechnique Fédérale de Lausanne (EPFL) CH - 1015 Lausanne, Switzerland

2. Action list decided in Lausanne, May 2007 • New data • JFT-2M, CHS (TT, done during the meeting) • NSTX (SK, before next meeting) • MAST (MV, tbd) • Data check • CMOD (JS, 30 June) • Description of data selection criteria (YM, 31 May + next meeting) • In the paper – tb discussed • New version of DB • data checked IGDBTH4v6c (asap, CMOD) • New data: IGDBTH4v7 (before next meeting) done without MAST and NSTX • Recommended scaling • Estimation with changes in data selection (asap, data checked) • Errors, Kadomtsev constraint(before next meeting) ... tb discussed

3. Action list decided in Lausanne, May 2007, cntd • Density dependence of threshold power • Done in the paper • Identify dedicated density scans in threshold DB (CMOD, done during meeting, others: 31 May) Not used in paper/not done • Verify if experiments were done and not in threshold DB, then provide data (All, 30 June) Status? • Density at minimum threshold power • Joint experiment proposed (CDB-10) • DB analysis done for the paper • Power ratio (PL/Pthresh) in good confinement regimes • Identify published good confinement results which are not included in the confinement DB (All, 30 June) and provide data • Extract evolution of power ratio for a few typical discharges (All, 15 August) • Search for evolution of power ratio in ITER scenarios (YM, 30 June) ... tb discussed

4. Action status – New data • No new data sent from MAST, NSTX • Action ? • Continue waiting • Stop waiting • Waiting: • NSTX SK ? • MAST MV ?

5. Action status – recommended scaling ... • New version of the database released on 15.8.2007 • IGDBTH4v7 • Contains: new data from CHS & JFT2M, corrected CMOD data and selection parameter (SELEC2007) • Corrected version on 27.8.2007 • Selection criteria • Phase=LDL removed for AUG • Phase=D removed CMOD • Checking DB: code to select any tiny change between two versions • Issue of format • Recommended scaling • In paper ... tb discussed • Density dependence, minimum threshold power, PL/PThresh, ... • In paper ... tb discussed

6. Sensitivity study • Received from R.Stambaugh, June 12th: • You are requested by the ITER Design Review Working Group #1, Design Requirements and Physics Objectives, to perform the task described as input to the ITER Design Review. • Part of the DR&PO Working Group's Task 2, Sensitivity Studies • Impact on ITER performance objectives of operating at 10% lower toroidal field • Received a spreadsheet with data corresponding with variants of the ITER standard scenarios at -10% toroidal field. Also included: variants which recover full performance by lowering little q, raising density, raising confinement H, raising stability (betaN), or raising elongation at full minor radius

7. Sensitivity study: Tasks • Task 2.1. Spreadsheet Scalings from the Baseline Scenarios • Task 2.2 Scenario Variation Assessments Using Calibrated 1-D Transport Models. • Task 2.3. Scenario Variation Assessments Using 1-D Codes With First Principles Transport Models. • Task 2.4. Operating Space Diagrams • Task 2.5. Projections of Advanced Operating Modes from Current Experiments. • Task 2.6. Secondary and More Detailed Consequences of Scenario Variations • 2.6.1. L-H Transition Threshold Power • 2.6.2. Impact on NNBI voltage and/or shinethrough issues ITER-IO • 2.6.3. Impact on ICRF application • 2.6.4. Impact on ECH/ECCD application, including NTM situation • 2.6.5. Risk of operating at lower q to recover fusion power • 2.6.6. Density limit and confinement at high densities • 2.6.7. General shift to higher required bN to recover fusion power as BT is reduced, with attendant increased need for wall stabilization • 2.6.8. AE mode behavior • 2.6.9. ITER support toward DEMO, including power handling issues, steady-state, etc. • 2.6.10. Impact on TBM program

8. Sensitivity study: report • Introduction • Influence of the main toroidal field reduction • Reduction of the threshold power (from ~90MW to ~80MW at 1020m-3) • Sensitivity around reduced field reference • Raise plasma current: low q95 values, difficult to quantify, selection criteria to avoid low q95, ITER: at q95=2.8, threshold might increase • Increase H98y2 with reduced power: difficult to achieve • Increase density: Increase in threshold power but still lower than original scenario • Increase elongation: increased threshold power if q95 and Greenwald fraction maintained • Decrease T,b,external power: difficult to achieve • General comment on ITER threshold power at high density • Threshold power 2-3 larger than indicated in Table and larger than available power (hysteresis, PL/Pthresh, density of minimum threshold, ...)

9. Talks • Scaling of the L-H Transition at Low Density in C-Mod • A. Hubbard (J. Snipes) • Validation of DIII-D H_98y2 factor in Power Threshold Database • J. Deboo (G. Wang) • Sensitivity of L-H power threshold to rotation in DIII-D (given yesterday) • P.Gohil • Address Mukhovatov questions on ITER guidelines • Reports of data submissions, analyses, discussion of IAEA H-mode Meeting paper, etc