Role of Stable Modes in the ITG-Driven Instability in a Mode-Coupled System

• HILSCHER Paul P.

  Graduate School of Energy Science, Kyoto University

• IMADERA Kenji

  Graduate School of Energy Science, Kyoto University

• LI Jiquan

  Graduate School of Energy Science, Kyoto University

• KISHIMOTO Yasuaki

  Graduate School of Energy Science, Kyoto University Institute of Advanced Energy, Kyoto University

Abstract

Kinetic damping in linear gyrokinetic (GK) Vlasov simulations is found to exhibit a bifurcation at the collisionality β_c = β^*_c , above which, i.e. β_c >β^*_c , the damping is represented by a Landau eigenmode in velocity space, while below which, i.e. β_c < β^*_c , by the phase mixing of a finite number of marginally stable, discretized Case-van Kampen eigenmodes. The latter causes a recurrence that restricts the damping and then the energy transfer from wave to particles within a finite recurrence time. In order to address whether the stabilization effect due to such stable damped modes on unstable modes via mode coupling can be evaluated in long timescale GK simulations, we introduced a triad model consisting of stable and unstable modes incorporated with a tertiary vortex flow. We identified β^*_c numerically and found that the stabilization effect works properly beyond the recurrence time even in the phase mixing regime across β_c = β^*_c .

Journal

• Plasma and Fusion Research

  Plasma and Fusion Research 8 (0), 1303151-1303151, 2013

  The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

• gyrokinetics
• Landau damping
• Case-van Kampen eigenmode
• mode coupling

Details

• CRID: 1390001205254553344
• NII Article ID: 130003392939
• DOI: 10.1585/pfr.8.1303151
• ISSN: 18806821
• Web Site: https://www.jstage.jst.go.jp/article/pfr/8/0/8_1303151/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed