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Title: Observation of upper drift modes in radio frequency produced magnetized plasmas with frequency above ion cyclotron frequency

In a RF produced magnetized argon plasma expanding into a larger expansion chamber, electrostatic modes propagating azimuthally in the direction of the electron diamagnetic drift and frequency greater than the ion cyclotron frequency are observed. In the radial direction, the mode amplitude peaks at a location where the radial density gradient is maximum. The modes are detected at axial locations up to 16 cm away from the entrance aperture. For fixed values of the neutral pressure and magnetic field, the mode frequency is found to be independent of the location at which it is measured. The modes exhibit drift wave characteristics revealing a radial structure with the azimuthal mode number m = 1 at the lower radial locations (r ∼ 3.0 cm) while the m = 2 mode is located in the outer region. Theoretical modeling using a local dispersion relation based on the fluid equations predicts destabilization of the modes with frequency greater than the ion-cyclotron frequency by electron-neutral collisions and exhibiting other drift wave features.
Authors:
; ; ;  [1]
  1. Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)
Publication Date:
OSTI Identifier:
22489916
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 12; Other Information: (c) 2015 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; AMPLITUDES; ARGON; CYCLOTRON FREQUENCY; DISPERSION RELATIONS; ELECTRON COLLISIONS; EXPANSION CHAMBERS; FLUID MECHANICS; ION CYCLOTRON-RESONANCE; MAGNETIC FIELDS; NEUTRAL PARTICLES; PLASMA; RADIOWAVE RADIATION; WAVE PROPAGATION