Fast excitation of geodesic acoustic mode by energetic particle beams

Jintao Cao, Zhiyong Qiu, Fulvio Zonca

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A new mechanism for geodesic acoustic mode (GAM) excitation by a not fully slowed down energetic particle (EP) beam is analyzed to explain experimental observations in Large Helical Device. It is shown that the positive velocity space gradient near the lower-energy end of the EP distribution function can strongly drive the GAM unstable. The new features of this EP-induced GAM (EGAM) are: (1) no instability threshold in the pitch angle; (2) the EGAM frequency can be higher than the local GAM frequency; and (3) the instability growth rate is much larger than that driven by a fully slowed down EP beam.
Original languageEnglish
Article number124505
Pages (from-to)-
JournalPhysics of Plasmas
Issue number12
Publication statusPublished - 1 Dec 2015
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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