Publications
Farzad Sadjadi
Determining the Work Function of Tungsten Through Thermionic Emission MeasurementsF. Sadjadi, Proceedings of the 127th AAPT National Meeting (Summer 2003)
Abstract
In this paper the work function of tungsten is determined through the measurement of thermionic emission as a function of filament current. The current induced in an anode by the emitted electrons from a hot wire filament was recorded as a function of the potential difference between the filament and the anode (repeating for different filament currents). The filament was placed in a chemical vacuum to remove the effects of the air particles on the observations. From this data the work function of the filament was calculated using the Richardson-Dushman equation modified for the effects of space charge. The use of this equation necessitated the input of temperature data for the filament which was taken to be proportional to the filament current. The experimentally derived value of the work function of tungsten was 4.511�0.0045 which is in good agreement with the standard values of between 4.52 and 4.32