A study of thermionic emitters in the regime of practical operation

Abstract

In many important applications of thermionic emitters, such as TWT's, the operating point of the device is chosen to be in the space charge limited region, In practice this point is usually not too far from where the device transitions to saturated emission. A detailed analysis of the current density-Voltage-Temperature (J-V-T) relationship in many devices in this region of operation shows large discrepancies with currently accepted emission theories, These discrepancies make the (J-V-T) characteristics unusable as a means of studying emitters in their real operating environment, An earlier reported (IEDM 1978) empirical relationship for the current density-Voltage-Temperature will be shown to be an accurate representation of experimental data, in all device geometries tested. A summary of some of the experiments will be discussed and compared to both Langmuir's emission theory and the empirical discovered relationship, Finally, some fundamental physics will be discussed that is felt will support the existence of the cited empirical relationship.