Influence of a DC Field on the Near-Electrode Zone of Nonuniform Microwave Discharge in Hydrogen

We investigate, by the emission spectroscopy, the influence of the DC electric field on the near-surface plasma of the electrode microwave hydrogen discharge (EMD) at pressures of $1$ to $5$ Torr. We obtain the DC current-voltage characteristics of the EMD, the strength values of the microwave field, and its spatial distributions in the EMD near-electrode zone. Under a positive voltage on the electrode as against the chamber, the variation in the discharge structure are minor, and, at the particular voltages depending on the pressure and the microwave power, the spatial charge layer breakdown takes place near the discharge chamber surface. Under a negative voltage on the electrode (the plasma cathode microwave mode), the discharge structure and dimensions vary and, at high currents, the discharge cancels.