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Title: Fast excitation of geodesic acoustic mode by energetic particle beams

Abstract

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.

Authors:
 [1];  [2];  [3]
  1. Institute of Physics, Chinese Academy of Science, Beijing (China)
  2. Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou (China)
  3. ENEA C. R. Frascati, C.P. 65, 00044 Frascati (Italy)
Publication Date:
OSTI Identifier:
22489989
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 22; Journal Issue: 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; DISTRIBUTION FUNCTIONS; EXCITATION; GEODESICS; INCLINATION; INSTABILITY GROWTH RATES; LHD DEVICE; MATHEMATICAL SPACE; PARTICLE BEAMS; SOUND WAVES; VELOCITY

Citation Formats

Cao, Jintao, Qiu, Zhiyong, Zonca, Fulvio, and Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou. Fast excitation of geodesic acoustic mode by energetic particle beams. United States: N. p., 2015. Web. doi:10.1063/1.4938277.
Cao, Jintao, Qiu, Zhiyong, Zonca, Fulvio, & Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou. Fast excitation of geodesic acoustic mode by energetic particle beams. United States. https://doi.org/10.1063/1.4938277
Cao, Jintao, Qiu, Zhiyong, Zonca, Fulvio, and Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou. 2015. "Fast excitation of geodesic acoustic mode by energetic particle beams". United States. https://doi.org/10.1063/1.4938277.
@article{osti_22489989,
title = {Fast excitation of geodesic acoustic mode by energetic particle beams},
author = {Cao, Jintao and Qiu, Zhiyong and Zonca, Fulvio and Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou},
abstractNote = {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.},
doi = {10.1063/1.4938277},
url = {https://www.osti.gov/biblio/22489989}, journal = {Physics of Plasmas},
issn = {1070-664X},
number = 12,
volume = 22,
place = {United States},
year = {2015},
month = {12}
}