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Title: Diocotron modulation in an electron plasma through continuous radio-frequency excitation

The application of a radio-frequency (RF) excitation to any electrode of a Penning-Malmberg trap may result in significant electron heating and ionization of the residual gas with the formation of a plasma column when the RF frequency is of the order or larger than the typical axial bounce frequencies of few-eV electrons. The use of a quadrupolar excitation can induce additional phenomena, like formation of dense, narrow-cross section columns which exhibit an m{sub θ}=1 diocotron mode, i.e., a rotation of their center around the trap axis. A series of experiments is presented and discussed showing that the continuous application of such excitation causes a dramatic perturbation of the plasma equilibrium also involving continuous production and loss of particles in the trapping region. In particular, the growth of the first diocotron mode is suppressed even in the presence of ion resonance and resistive instability and the mode exhibits steady-state or underdamped amplitude and frequency modulations, typically in the Hertz range.
Authors:
; ; ;  [1]
  1. Dipartimento di Fisica, Università degli Studi di Milano and I.N.F.N. Sezione di Milano, Via Celoria 16, 20133 Milano (Italy)
Publication Date:
OSTI Identifier:
22403316
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 12; Other Information: (c) 2014 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; ELECTRONS; EQUILIBRIUM; EXCITATION; FREQUENCY MODULATION; PLASMA; RADIOWAVE RADIATION; STEADY-STATE CONDITIONS; TRAPS