Emission characteristics of an electron source with a plasma surrounded by an ion sheath at the wall

The characteristics of an electron source based on emission from a plasma surrounded by an ion sheath at the wall are analyzed including the processes taking place in the emission channel. A physical model and method are proposed for calculating the current-voltage characteristics, the emission characteristic, and the control characteristics of the source as functions of the plasma parameters, field strength in the accelerating gap, and the geometry of the emission channel. It is shown that passage of an emission current through the plasma in the channel does not lead to significant changes in the axial density distribution. The computational results are in satisfactory agreement with experimental data. 7 refs., 4 figs