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Title: Controllable transition from positive space charge to negative space charge in an inverted cylindrical magnetron

The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode. It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lowermore » magnetic field.« less
Authors:
; ;  [1] ;  [2]
  1. FCIPT, Institute for Plasma Research, Gandhinagar-382044 (India)
  2. ITER-India, Institute for Plasma Research, Gandhinagar-382044 (India)
Publication Date:
OSTI Identifier:
22493863
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 1; Other Information: (c) 2016 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; ANODES; ARGON; CATHODES; CYLINDRICAL CONFIGURATION; DIFFUSION; DISTANCE; ELECTRIC DISCHARGES; ELECTRONS; MAGNETIC FIELDS; MAGNETRONS; PLASMA POTENTIAL; PRESSURE DEPENDENCE; SPACE CHARGE