Oscillographic Studies of Joshi Effect and Secondary Processes in a Low Frequency Electric Discharge

Abstract

Low frequency (50 cycles/sec) electric discharge in iodine vapour with glass electrodes was investigated by a cathode ray oscillograph. The rms value of the conductivity was contributed chiefly by two types of pulses, the electron avalanches of which were produced by secondary electrons originating from the cathode and the gas phase. The secondary process concerned with the liberation of electrons from the cathode due to positive ionic bombardment thereon appeared significant for the onset, of the discharge under investigation. The maintenance of the discharge seemed primarily due to photo-ionization of the gas particles in the homogeneous phase. External radiation inhibited the secondary emission from the cathode to give negative Joshi effect, and enhanced that from the gas phase to produce positive Joshi effect; it, however, did not alter the field gradient in the system.