High Frequency Discharges in Gases

Abstract

IN the issue of NATURE for Feb. 4, Messrs. Taylor describe a ‘new form’ of high frequency discharge in gases at low pressures. This type of discharge is one of those which may be obtained when the gas is acted upon by an oscillatory force, derived either from a Tesla transformer where the oscillations are damped or from a generator performing continuous oscillations, and they occur in various forms, many of which are quite well known. The methods of maintaining continuous oscillations at high frequency by means of valves have added additional interest to electrodeless discharges as they provide a means of attaining a steady state of ionisation in the gas so that the currents and the potentials at the electrodes corresponding to the various forms of the discharge may be accurately measured. For this reason they have been included in the experimental courses in Oxford, and doubtless at other universities, and it may be of interest to describe a few of the more striking features which can be made the subject of simple experiments. Luminous discharges in gases may be maintained with long wave oscillations or with oscillations of a few metres wave-length. The resulting phenomena are much the same whether the potentials be applied between external or internal electrodes.