Theory and observations of high frequency Alfvén eigenmodes in low aspect ratio plasmas

N. N. Gorelenkov, E. Fredrickson, E. Belova, C. Z. Cheng, D. Gates, S. Kaye, R. White

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

Abstract

New observations of sub-cyclotron frequency instability in low aspect ratio plasmas in national spherical torus experiments are reported. The frequencies of observed instabilities correlate with the characteristic Alfvén velocity of the plasma. A theory of localized compressional Alfvén eigenmodes (CAE) and global shear Alfvén eigenmodes (GAE) in low aspect ratio plasmas is presented to explain the observed high frequency instabilities. CAEs/GAEs are driven by the velocity space gradient of energetic super-Alfvénic beam ions via Doppler shifted cyclotron resonances. One of the main damping mechanisms of GAEs, the continuum damping, is treated perturbatively within the framework of ideal MHD. Properties of these cyclotron instability ions are presented.

Original languageEnglish
Pages (from-to)228-233
Number of pages6
JournalNuclear Fusion
Volume43
Issue number4
DOIs
Publication statusPublished - 2003 Apr 1

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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