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Title: Instability limits for spontaneous double layer formation

We present time-resolved measurements that demonstrate that large amplitude electrostatic instabilities appear in pulsed, expanding helicon plasmas at the same time as particularly strong double layers appear in the expansion region. A significant cross-correlation between the electrostatic fluctuations and fluctuations in the number of ions accelerated by the double layer electric field is observed. No correlation is observed between the electrostatic fluctuations and ions that have not passed through the double layer. These measurements confirm that the simultaneous appearance of the electrostatic fluctuations and the double layer is not simple coincidence. In fact, the accelerated ion population is responsible for the growth of the instability. The double layer strength, and therefore, the velocity of the accelerated ions, is limited by the appearance of the electrostatic instability.
Authors:
 [1] ;  [2] ; ; ; ; ;  [1] ;  [1] ;  [2] ;  [3]
  1. Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States)
  2. (United States)
  3. Department of Physics and Engineering, West Virginia Wesleyan, Buckhannon, West Virginia 26201 (United States)
Publication Date:
OSTI Identifier:
22218459
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 11; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CORRELATIONS; ELECTRIC FIELDS; ELECTROSTATICS; FLUCTUATIONS; IONS; PLASMA DIAGNOSTICS; PLASMA EXPANSION; PLASMA INSTABILITY; PLASMA SHEATH; PLASMA WAVES; TIME RESOLUTION