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ITPA – CDBM H-mode threshold database Discussion October 2007 - Naka. Yves Martin Centre de Recherches en Physique des Plasmas Association Euratom - Confédération Suisse Ecole Polytechnique Fédérale de Lausanne (EPFL) CH - 1015 Lausanne, S witzerland. Outline. Mukhovatov's note
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ITPA – CDBMH-mode threshold databaseDiscussionOctober 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
Outline • Mukhovatov's note • Joint experiments (CDB-10, ...) • Density threshold • Rotation • Hysteresis • Transitions between type III and type I ELMs
Vladimir Mukhovatov's note • H-mode Threshold Power: ITER needs • Scaling with toroidal magnetic field of plasma density (nmin) at minimum L-H threshold power • L-H threshold power as a function of magnetic ripple amplitude at the same n and B (Task for JET) • Scaling for power threshold PTypeI for transition from Type III to Type I ELMy H-mode at high triangularity (~0.4-0.5) • Scaling for power threshold for back transition from Type I ELMs to Type III ELMy H-mode at high triangularity (~0.4-0.5)
Density threshold • After C-Mod contribution ... • Following paper content ... • Characterisation of density threshold • Dependence on magnetic field, divertor geometry, plasma geometry, neutrals, plasma current, ... • New experiments ?
Rotation data in threshold DB • JT-60U data – Edge toroidal rotation
Rotation • What can we do ? • DIII-D data ? • Send data to DB ? • Other devices ? • Presentations from individual devices ? • Who ? • New data (new time slices or rotation data) in the DB ? • Continue with VTO95 and VPO95 or add other vars ?
Hysteresis from DB • Extract plasma characteristics for time slices data with good confinement at power ratio close to 1. • Compare characteristics to average operational conditions
Hysteresis foreseen in ITER • Entering H-mode at low density (0.5 x 1020m-3) • Maintain input power above H-L transition threshold while increasing the density up to nominal value (1.0 x 1020m-3) • Increase the power until good confinement (H=1) is obtained
Hysteresis experiments in present day devices • Obtain H-mode at low density (tbd) with minimum required power • Characterise H-mode quality (ELM type) during 'natural' density increase/excursion while maintaining the power constant (close to threshold) • With power ramps or single steps • Power maintained at Pthresh * 1.0 (ideally) or 1.1 or 1.2 • Increase the density while maintaining the power constant
Threshold power between ELM types • JET results for ELM type transition (and sustainment) • PIII-I = Y x Pth where 1.5<Y<2.5 • In the literature • Provide some info • In the DB • Correlation between small / big ELMs and type III / I ELMs • New experiments • Threshold studies similar to those for L-H transition • who?