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Initial Boron Powder Injection Experiments on WEST

POSTER

Abstract

Boron powder (< 150 mm) was injected at various drop rates into lower single null (LSN) L-mode discharges in WEST, using a recently installed impurity powder dropper (IPD) developed at PPPL. IPDs provide real-time wall conditioning of plasma-facing components without the use of diborane gas. The long-pulse capabilities of WEST and the full-W environment make it an excellent testbed for evaluating the viability of the IPD at reactor relevant timescales. The discharges presented featured  Ip ~ 0.5 MA, tpulse = 12-30 s, ne,0 ~ 4x1019 m-3, and PLHCD ~ 4.5 MW. During powder injection, a clear reduction in SOL D I and low-Z intrinsic impurity line intensities was observed, suggesting a reduction in recycling and possible screening of low-Z impurities. Concurrently, the plasma stored energy increased up to 25% depending upon the powder drop rate. The largest increases in stored energy were achieved at the highest drop rates (9-17 mg/s), possibly due to the large reduction in divertor recycling. Initial analysis suggests these increases in stored energy may be the result of stabilized ion temperature gradient (ITG) modes due to fuel dilution similar to gaseous impurity seeding experiments.

Presenters

  • Grant Bodner

    Princeton Plasma Physics Laboratory

Authors

  • Grant Bodner

    Princeton Plasma Physics Laboratory

  • Alessandro Bortolon

    Princeton Plasma Physics Laboratory

  • Clarisse Bourdelle

    CEA-IRFM, CEA

  • Ahmed Diallo

    Princeton Plasma Physics Laboratory

  • Alberto Gallo

    CEA, CEA-IRFM, CEA-Cadarache

  • Christophe Guillemaut

    WEST, CEA Cadarache - France, CEA-IRFM, CEA Caderache

  • James P Gunn

    WEST, CEA Cadarache - France, CEA-IRFM, CEA-Cadarache, CEA IRFM

  • C.Christopher Klepper

    Oak Ridge National Lab

  • Robert A Lunsford

    Princeton Plasma Physics Laboratory

  • Philippe Moreau

    CEA-IRFM

  • A. Nagy

    PPPL, Princeton Plasma Physics Laboratory

  • Francis-Pierre Pellissier

    CEA-IRFM

  • Emmanuelle Tsitrone

    CEA-IRFM, CEA-Cadarache

  • Ezekial A Unterberg

    Oak Ridge National Lab, Oak Ridge National Laboratory

  • Laure Vermare

    LPP-École Polytechnique