Characteristics of the Electrode Plasma of an Electrode Microwave Discharge in Hydrogen

The electrode region of an electrode microwave discharge in hydrogen at pressures of 0.5–4 torr and absorbed powers of up to 12 W is studied using emission spectroscopy and actinometry. It is shown that the gas temperature is at most 700 K and the degree of dissociation does not exceed several percent. Direct electron impact is shown to be the main factor governing all the processes in the electrode region of the discharge, including the excitation of the recorded emission. In particular, the Balmer-series H_α line emission is related to the dissociative electron-impact excitation of hydrogen molecules in the ground state.