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TC-2 – Power ratio April 2011, San Diego

TC-2 – Power ratio April 2011, San Diego. 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. Introduction Status Results from devices Synthesis

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TC-2 – Power ratio April 2011, San Diego

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  1. TC-2 – Power ratioApril 2011, San Diego Yves Martin Centre de Recherches en Physique des Plasmas Association Euratom - Confédération Suisse Ecole Polytechnique Fédérale de Lausanne (EPFL) CH - 1015 Lausanne, Switzerland

  2. Outline • Introduction • Status • Results from devices • Synthesis • Next step(s) • Discussion on TC-2 contribution to H-mode WS

  3. Introduction TC-2 • Goals of TC-2 • Characterise existing data with PL/Pthresh~1 and H~1 • Identify stationary phases in each device • Characterise the plasma conditions • Compare findings • Test a discharge scenario to reach a H~1 regime at high density (0.8 nGr) with minimum additional power • L-H transition at low density (0.4 nGr) with P~Pthresh • Characterise confinement (H factor, ELMs, …) • Move to the target density of 0.8 nGr (naturally + ev. gas puff) without increasing power • Characterise confinement (H factor, ELMs, ...) • Increase power either before L-H transition or during density ramp to reach H~1

  4. Status • Input from • ASDEX Upgrade • Alcator C-mod • DIII-D • JET • NSTX • TCV

  5. ASDEX Upgrade • Identification • F.Ryter et al. JPCS (2008) 012035 • PLTH/PThr<1.6; 3<q95<6; large density range • H~1 with PLTH~PThr. Type I ELMs – higher pedestal pressure • bN~2 with PLTH/PThr~1.2 • Some data with PLTH/PThr<1; type III ELMs with reduced confinement • Density saturation at n/nG~0.7 in type I ELMs • At higher triangularity. With slow ELMs (large ELMS?!(YM)) • Hysteresis • Back transition, H-L, known to occur at lower power • Dedicated experiments recently done

  6. Alcator C-mod • Identification • J.W.Hughes et al. IAEA 2010 • Little data at PLTH/PThr~1. More around 1.5. • PNET, including core radiated power, better aligns EDA and ELMy H-modes in H98y2 vs PLTH/PThr plan • Hysteresis • Clear hysteresis (x2) in PLTH ramp-down

  7. DIII-D • Identification • E.J.Doyle: APS DPP, 2010 • Reference cases for ITER, both H98y2~1 • High density, PLTH/PThr~1, large ELMS • Low density, PLTH/PThr>>1, ITER collisionality

  8. JET • Identification • PL~1.6 x Pscal @ ne/nG ~ 0.4 • For H~1, PL ~ 2 x PScal. • Type I ELMs • E.de la Luna, M.Beurskens, PEP29, ITPA PEP 2011 • Vertical kicks

  9. NSTX • Identification • H-L transition at PL<PTh (less dependent of density) • H~1 with PL~PTh. Done with RF/NB in He/D, ELM free, but not crystal clear (shaping?)

  10. TCV • Identification • Ohmic H-mode, PLTH/PThr~1, H98y2<<1 • ECH H-mode, PLTH/PThr>>1, H98y2~1 • Hysteresis • Experiments planned

  11. Synthesis - Main trends • Starting point • Most machines usually operate at PLTH/PThr>>1 to obtain H98y2<<1 • Identification of discharges at PLTH/PThr~1: done • Large, low frequency ELMs • Same cases with more tolerable ELMs, but in specific conditions • More and more awareness in talks, papers, … • Hysteresis Joint Experiment • Hysteresis observed in many devices in P ramp downs • TC-2 scenario not performed

  12. Joint experiment • Goal • Operate a device in high density, good confinement, H-mode with an available power close to the H-mode threshold power • Obtain H-mode at low density, low power • Increase density without increasing power • Relies on • Hysteresis (PLTH/PThr<1) • Good confinement close to threshold • Fueling H-mode plasma in large devices • … L-H transition in current ramp • …

  13. Joint experiment • Goal • Map discharge evolution in H98y2 vs PLTH/PThr plan • With existing data • With data from the dedicated experiment • Important for ITER scenario preparation

  14. Scope of the H-mode WS Contribution • Introduction • ITER requirements (ITER, threshold power, H-D-DT phases, scenarios, …) • Summary of the experiments • Device by device • Synthesis – Discussion • Main trends • Compatibility with ITER • Joint experiment • Existing trajectories • Our plans / intentions • Conclusion • Path to the success ? • Warning ?

  15. Organisation - Agenda • Analysis • 2 months • Abstract • 30.6.11 • Paper • Not required, decide later ? • Requirements • Commitment from all representatives • Most recent dedicated publications, all relevant • Data of discharge evolution

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