Experiments on the excitation of light by low voltage positive rays

Abstract

Although the ionisation and excitation by low voltage electrons have been extensively studied experimentally, and the general course of these processes is fairly well mapped out, the phenomena of ionisation and excitation by slow positive ions have so far been but little attacked, and what experimental material exists is rather inconclusive. The well-known formula for the current in a cumulative gaseous discharge was based upon the assumption that slow positive ions were capable of ionising the gas molecules they struck; and the accuracy with which this formula fitted the experimental results was taken as good evidence for the physical assumptions leading to it. But Holst and Oesterhuis have suggested that in addition to the ionisation produced by the moving positive ions the secondary electron emission from the cathode produced by the impact of positive ions (a phenomenon otherwise demonstrable) plays an important rȏle. This process, if it occurs, must render uncertain any quantitative conclusions as to ionisation by positive ions drawn from the classical formula.