Legend about photoemission discharge

It is shown that the currently advertised ‘new form of discharge’ (open discharge) — photoemission with a virtually noneroding cathode and ‘anomalously high’ (near unity) energy efficiency of electron beam (EB) formation — cannot, in fact, be implemented. In reality, such a discharge fits well into the familiar pattern of glow discharges controlled by heavy particle emission. Thus, in known EB sources, an energy efficiency of up to $\approx 0.8$ is ensured by fast atoms from ion charge exchange in strong discharge fields. However, charge multiplication and cathode-directed ion drift are both proportional to the flux of cathode electrons (including photoemitted ones), implying that the energy efficiency cannot increase through its contribution. It is this incorrect efficiency measurement methodology which gives the result of an efficiency approaching unity.