The Plasma Physics of Thermionic Converters

The plasma physics of thermionic converters is discussed in an attempt to develop a coherent physical picture of this aspect of the converter in all regions of operation. Emphasis is placed on the presentation of simple physical models consistent with experimental data: The usefulness of certain characteristic features of the I–V curve, in determining the physical processes governing converter operation, is pointed out. Nine regions of converter operation are identified by these features of the I–V curve and are discussed. The importance of two parameters of converter operation, the pressure—spacing product pd, and the relative amount of emitter-surface ion generation β, in controlling converter behavior is emphasized. The particular values of pd and β control which of the nine regions of converter operation appear on a particular I–V curve.