Energy Exchanges Attending Field Electron Emission

Abstract

The energy exchange attending field electron emission (Nottingham effect) is shown to be localized to the emitting area of the cathode. It is further shown that the magnitude and direction (i.e., heating or cooling) depend strongly on cathode temperature, work function, and applied electric field. The temperature boundary separating emission cooling and heating is considerably below theoretical expectations for clean and for zirconium-oxygen-coated tungsten. The existing theory of the Nottingham effect, examined in the light of these and other results, must be modified to include the variation of average energy of the conducting carriers with temperature and field.