Stability analysis of experimental high-beta toroidal plasmas

A. G. Kellman, M. W. Phillips, S. C. Prager, M. C. Zarnstorff

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Previously, the production of stable high-beta plasmas in the University of Wisconsin Levitated Toroidal Octupole has been reported. The plasma beta measured in the bad-curvature region ranges from β - 8% to 44% (n e≈ (2-5) × 1013 cm−3, B pol≈ 200-860 G) in macroscopically stable plasmas with decay times in excess of 1000 Alfvén times. In this paper, theoretical work performed on non-MHD effects to explain the significant enhancement of plasma stability above the ideal-MHD ballooning instability limit of 4% is described. The effects are included in finite-n MHD theory and a detailed kinetic treatment including finite Larmor radius (FLR) and heat flow along field lines. The FLR effects are sufficient to explain the stability of the β = 8% plasma through coupling of the ballooning mode to a stable oscillatory ion drift wave. This cannot explain the stability of the more collisional, larger-gyroradius β = 44% plasma. Equilibrium diamagnetism is strongly affected by ion gyroviscosity in this plasma, and the role of this effect on the equilibrium and stability is discussed.

Original languageEnglish (US)
Pages (from-to)1561-1574
Number of pages14
JournalNuclear Fusion
Volume23
Issue number12
DOIs
StatePublished - Dec 1983
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Condensed Matter Physics

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