Size effect of nanometer vacuum gap thermionic power conversion device with CsI coated graphite electrodes

Cesium iodide (CsI) coated graphite is a good candidate for an electrode material of a thermionic power generation device due to its low work function. In this letter, a thermionic device with a nanometer-scale vacuum gap between a CsI coated graphite emitter and a collector will be investigated while considering various gap-size effects. It is shown that a nanometer scale gap-size not only affects electron transport but also photon transport, and that all of these effects must be taken into account when estimating the device's performance.