Production ofJoshi-Effect in air under electrical discharge: The Rôle of sorbed chlorine

Summary

Observations ofJoshi-Effect Δi, were made in (a) air, (b) chlorine, (c) chlorine-air mixtures and (d) air with sorbed chlorine, under an ozoniser discharge, in the range 1–3 kilo-volts (r.m.s.), of 500 cycles frequency, using as detectors an oxide rectifier and a vacuo-junction connected in series. Theeffect was undetected with the available means in (a) even when mixed with traces of chlorine; it was as high as 80% current diminution in but ordinary light in (b) and (c), and remarkably enough also in (d). Whilstaging in (b) and (c) increased Δi. that in (d) reduced it. This decrease in (d), attributable to the desorption of chlorine, was markedly rapid when the system was filled with successive samples of air subjected to discharge and toplered out (but notdegassed); finally Δi was negligibly small as in (a). The large Δi in (d) is due to sorption of chlorine under conditions of discharge and not that resulting from prolonged contact of neutral chlorine with the container walls or streaming preactivated chlorine through the ozoniser. These results confirm Joshi's theory that an adsorption-like boundary layer formed under discharge is the chief seat of Δi.

Compared with the oxide rectifier, the vacuo-junction recorded a lower Δi. Following Joshi, this is ascribed to a selective action of the former to some of the frequencies constituting the discharge current.