Analysis of a hollow-cathode reflex discharge in a hydrocarbon flow

Abstract

Variation of parameters of a reflex discharge with a hollow cathode operating continuously in propane with a flow rate of 1.3–5.6 (m3 mPa)/s and a discharge current of 0.1–0.4 A is analyzed. It is shown that for a hydrocarbon flow rate of 2.4 (m3 mPa)/s and higher, an increase in the discharge voltage takes place after a time interval depending on the discharge current and gas pressure; this is explained by the formation of coating of the dissociation products of hydrocarbon molecules on the electrodes of the discharge chamber. An increase in the thickness of the carbon coating of the cathodes with time and their charging with ions lead to electric breakdown of coatings and the formation of cathode spots. The oscillograms of the discharge current and voltage indicate a short-term transformation of the glow discharge into the arc discharge. The energy spectra of ions emerging from the discharge are measured, and the effect of the discharge current and the gas flow rate on the energy spread of ions is analyzed. The operation time of the discharge in hydrocarbon after which the cleaning of the discharge chamber is required is determined. The possibility of using an ion source based on the reflex discharge with a hollow cathode for technological purposes is established.