Predictions of HFS LHCD Absorption in DIII-D LH Commissioning Targets

POSTER

Abstract

High field side (HFS) lower hybrid current drive (LHCD) is predicted to improve accessibility and penetration over low field side launch, permitting efficient off-axis (⍴ ≈ 0.6-0.8) current drive. The first-ever HFS LHCD launcher has been installed on DIII-D and will be commissioned during the 2025 campaign. A set of target plasmas for commissioning has been identified for which high (50-100%) single pass absorption (SPA) is predicted, reducing the risk of undamped LH power damaging device components. These targets include a variety of plasmas, including L-mode and both toroidal field directions. Many are cleaning plasmas, allowing the bulk of commissioning to occur during startup, thereby making the best use of experimental run days. Due to mode conversion being the expected mechanism of N|| upshift, the optimal launched N|| for these plasmas can be counter-intuitive. This set of commissioning plasmas, together with a sensitivity study of the SPA on the launched N|| throughout the duration of each shot, is presented.

Presenters

  • Grant Rutherford

    MIT PSFC

Authors

  • Grant Rutherford

    MIT PSFC

  • Mirela Cengher

    MIT PSFC

  • Ivan Garcia

    MIT PSFC

  • Malcolm Gould

    MIT PSFC

  • Evan Leppink

    MIT PSFC

  • Yijun Lin

    MIT PSFC, MIT Plasma Science and Fusion Center

  • Samuel Pierson

    MIT PSFC

  • James Ridzon

    MIT PSFC

  • Andrew Seltzman

    MIT PSFC

  • Will Wright

    MIT PSFC

  • Stephen James Wukitch

    MIT, MIT PSFC