CI.<i>The electrodeless discharge through gases</i>

Abstract

Abstract This paper contains a discussion of the theory of the electrodeless discharge produced when a vessel containing gas at a low pressure is placed inside a solenoid, through which rapidly alternating currents produced by the discharge of Leyden jars are passing. It is shown that to produce the discharge the maximum magnetic force inside the solenoid must reach a value which depends (1) on the nature of the gas, (2) on its pressure, (3) on the frequency of the currents, (4) on the size of the vessel. This value is infinite when the pressure is either zero or infinity, it is a minimum when the pressure is such that λ p = c, where λ is the free path of the electron in the gas, p the frequency of the alternating current, and c the velocity of the electron when its energy is that required to ionize the gas. Thus there is a critical pressure when the discharge passes most easily, and this depends on the frequency of the currents. Experiments are described which confirm the truth of the theory. It is shown, too, that in the electrodeless discharge very large currents may pass through the gas without producing visible luminosity, so that luminosity of this kind involves processes in addition to the passage of a current. Within a certain range of pressures the gas is in a “ sensitive “ state, and the discharge has peculiar properties. Within a limited range of pressure and current density striations occur in the electrodeless discharge in hydrogen.