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

Journal Article · Tue Dec 15 04:00:00 EST 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4938507· OSTI ID:22489916

Ghosh, Abhijit; Saha, S. K.; Chowdhury, S.; Janaki, M. S. ^[1]

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1. Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

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.

• OSTI ID: 22489916
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 22; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

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