Spatial Distribution of Electron Concentration in a DC Glow Discharge Supported by a Hollow Cathode

For the first time, the spatial distribution of the electron density in the plasma region between the edge of the hollow cathode and the grid anode, which is not bounded by side walls, has been measured. The measurements were carried out in a discharge in helium at a pressure of 1.5 mbar using the original system for positioning of Langmuir probes in space. The dependence of the measurement results of the plasma electron component parameters on the cylindrical probe radius was investigated. The combined influence of the finite resistance of the plasma and the effect of the electron sink to the probe on the measurement results was analyzed.