LII. A determination of the energy distribution of electrons in the positive columns of gas discharges

Abstract

The electron energies in the positive column of low pressure hot cathode glow discharges have been examined by the magnetic spectrum method. From measurements of the energy distribution of electrons reaching a positive probe a method of finding the space potential is deduced. With this knowledge a comparison is made of the energy distribution of electrons, in the positive colunms of air and argon discharges, determined by the present method and the conventional probe method. Wide discrepancies are observed. The magnetic spectrum indicates a distribution of the Druyvesteyn tbrm whilst that deduced from probes is Maxwellian. The changing form of the distribution reaching negative probes is proof of the failure at these pressures of the assumptions on which Langmuir probe theory is based. Calculations by Boyd on positive ion sheath formation may give some indication of the mechanisms producing the changing distributiom