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Yves Martin Centre de Recherches en Physique des Plasmas

ITPA – CDBM H-mode threshold database Threshold power recommended scaling October 200 5 - St-Petersb urg. Yves Martin Centre de Recherches en Physique des Plasmas Association Euratom - Confédération Suisse Ecole Polytechnique Fédérale de Lausanne (EPFL) CH - 1015 Lausanne, S witzerland.

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Yves Martin Centre de Recherches en Physique des Plasmas

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  1. ITPA – CDBMH-mode threshold databaseThreshold power recommended scalingOctober 2005 - St-Petersburg Yves Martin Centre de Recherches en Physique des Plasmas Association Euratom - Confédération Suisse Ecole Polytechnique Fédérale de Lausanne (EPFL) CH - 1015 Lausanne, Switzerland

  2. Discussion plan • History • Scalings • Parameters, data selection, new data • Predictions • Summary • Questions • General (one single scaling ...) • Data selection • Variable selection • Method selection

  3. NF Paper 1996 - F.Ryter • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass-D, DIII-D, JET, JFT-2M, JT-60U, PBX-M • Nb of Samples: 3800

  4. IAEA 1996 - T.Takizuka • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass-D, DIII-D, JET, JFT-2M, JT-60U, PBX-M, TCV • Nb of Samples: 3860

  5. PPCF 1998 - E.Righi • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass-D, DIII-D, JET, JFT-2M, JT-60U, PBX-M, TCV • Nb of Samples: 3860

  6. PPCF 1998 - E.Righi - II • Analysis with edge parameters (nea & Tea) • => Tea for ITER (4.75keV +/- 1.9)

  7. PPCF 2000 - J.A.Snipes • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass, DIII-D, JET, JFT-2M, JT-60U, PBX-M, TCV • Nb of Samples: 6800 • Analysis of edge parameters => Te(90)

  8. PPCF 2002 - F.Ryter • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass, DIII-D, JET, JFT-2M, JT-60U, PBX-M, TCV • Nb of Samples: 6800

  9. PPCF 2004 - T.Takizuka • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass, DIII-D, JET, JFT-2M, JT-60U, MAST, NSTX, PBX-M, TCV, TUMAN-3M • Nb of Samples: ~7600 • Pth = 0.072 * n200.7 *|Bout|0.7 * S0.9 * (Zeff/2)0.7 * F(A)g

  10. IAEA 2004 - Y.Martin • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass, DIII-D, JET, JFT-2M, JT-60U, MAST, NSTX, PBX-M, TCV, TUMAN-3M • Nb of Samples: 7673

  11. IAEA 2003 - D.McDonald • Tokamaks: Alcator C-Mod, ASDEX, ASDEX Upgrade, Compass, DIII-D, JET, JFT-2M, JT-60U, MAST, NSTX, PBX-M, TCV, TUMAN-3M • Nb of Samples: 7673

  12. Tokamak Physics Basis • 2 Scalings included in TPB • From F.Ryter PPCF 2002: Pth = 0.042 * n200.73 *BT0.74 * S0.98 • Is based on • high density (to remove possible perturbation from turning point) • reduced tokamak list • normalisation of know dependences on individual tokamaks • Chosen because of its low RMS: 21.4% • From T.Takizuka, PPCF 2004 Pth = 0.072 * n200.7 *|Bout|0.7 * S0.9 * (Zeff/2)0.7 * F(A)g • Inlcudes more physics (Zeff, Bout)

  13. Summary of scalings - Threshold power Pthr ITER 8.1m [MW] Pthr ITER 6.2m [MW] 1996 2005

  14. Summary of scalings - coefficients

  15. Questions - general • Data was collected, new data added. • Database was analysed, different directions explored. • Many scalings were evaluated. • Questions: • Why 2 scalings in TPB? • Why not that one, with all tokamaks, which predicts lower threshold for ITER ? • Is it possible to nominate one scaling as THE reference scaling? • Which one ?

  16. Questions - Data selection • Selections used/proposed so far: • Standard data set (e.g. IAEA2004) • Increase/decrease strength of SELDB constraints (n, q95, ...) • Remove small tokamaks (ASDEX, COMPASS, TCV) • Remove spherical tokamaks • Remove electron heating • Select only NBI • Select/reject transition types (LDLDLD, ...) • Select/reject divertor types (open / close div., specific div.) • Select/reject plasma shapes (PBX-M: DND) • ... => Choice criteria ?

  17. Questions - Variable selection • Variables used so far: • n, B, Bout, a, R, Rmm, S, e, k, d, Zeff, • Variables evaluated so far: • ne90, Te90 • (a & R) or S • B or Bout • R or Rmm • ... => Choice criteria ?

  18. Questions - Method selection • Methods used so far • OLS • EVOR • ML • ... discriminant analysis • Dimensionally correct scalings

  19. Tools • Should we use • Other ways to present predictions • Confidence intervals for power coefficients • Threshold power with better description of confidence intervals • Other tools to predict ITER threshold power • Analysis of sensitivity on coefficients

  20. Conclusion • We decided to use • Data set: _______________________________ • Variable set: _______________________________ • Method: _______________________________ • Tools: _______________________________ • Because: _______________________________ • _______________________________ • _______________________________ • _______________________________

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