Electron energy distributions in plasmas - II. Hydrogen

Abstract

This paper is the second in a series of studies of low-pressure discharges in which an electronic method was used for the Druyvesteyn analysis of electron energy distribution. The method reported in the first paper (Boyd & Twiddy 1959) has been applied to the study of the mechanism of striation structure in hydrogen discharges, in the pressure range 0.01 to 0.1 mmHg and the current range 0.016 to 0.800 A. The basic relations governing the current flow, ionization rate and energy flux have been established and verified. These relations and this mechanism is not specific to hydrogen, as later papers will show. The measurements reveal insufficient electrons with energy capable of producing H$^+$ and H$_2^+$ directly, though it is possible that electrons having passed through two striation heads may make an important contribution. In view of earlier reports of the predominance of H$_3^+$ in such discharges it is tentatively suggested that the process H' + H$_2 \rightarrow$ H$_3^+$ + e may be important.