PRODUCTION OF THE JOSHI EFFECT IN OXYGEN UNDER SILENT ELECTRIC DISCHARGE. PART IV. INFLUENCE OF TEMPERATURE

Influence of temperature t on the Joshi effect Δi in oxygen, enclosed in a (sealed) Siemens' type glass ozoniser at 331 mm. pressure (32°), has been studied over 30° to 125° and 2 to 5 kilo-volts of so cycles frequency. At a constant applied V, the discharge current i increases markedly with t. The increase with t of the mobility of ions has been shown to be small. The current rise is attributed therefore to the increase with t of the dielectric conductivity, and from Joshi's equation of the dielectric cons­tant, of glass. The net effect Δi at constant V increases with t up to 50° and then decreases. The relative effect % Δi, on the other hand, decreases progressively. According to Joshi, formation on the excited electrodes of a boundary layer derived, in part, from a wall-adsorption of ions and other particles in the discharge space is primary to Δi. Electrons released from this layer on irradiation are captured by the electro-negative gas-elements to forms negative ions which produce Δi. Temperature would cause desorption and depolarization of the particles constituting the boundary lacer, and would inhibit negative ion formation, Decrease of Ai, as observed, follows.