The characterization of thermionic emission provided by a material occurs by measuring the emitted current as a function of the temperature (up to 1800 °C) at which the material is held. The measurements allow extrapolating work function and Richardson constant of the material, which are sufficient to completely depict its thermionic emission capability.
Typically, current-to-voltage characteristics are carried out in ultra-high vacuum conditions for the complete analysis of the device/material performance. Additionally, combined measurements for the study of more complex behaviors can be performed, by applying heating, electromagnetic radiation, and strong electric fields at the same time, useful for the evaluation of hybrid effects (e.g. photon-enhanced thermionic emission, thermionic-photovoltaic conversion etc.).
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