Revisiting the Luce diode in the context of recent research on multi-vircators with dielectric reflectors

Abstract

Recently, in a series of articles Mumtaz, Choi, and others [i.e., S. Mumtaz and E. Choi, IEEE Electronic Device Lett. 43, 1756 (2022)] studied a relativistic gridded vircator with one or more dielectric anodes, in which considerable increase in the efficiency of high-power microwave (HPM) generation compared to ordinary vircators was observed. This is very important since the main disadvantage of vircators is their low efficiency. It was suggested that the repelling of electrons by the initial impacting electron charge collected on the dielectric reflectors forms a multi-vircator, which increases HPM production. The present article reports the results of experiments and numerical simulations, which show that this mechanism does not result in high multi-vircator efficiency. Similar dielectric anodes were investigated 50 years ago in a configuration known as the Luce diode, in which collective acceleration of ions was studied. It was also known that the operation of the Luce diode is accompanied by a HPM burst, which was never measured. Results of experiments and simulations in various configurations based on a gridded vircator and dielectric reflectors confirm the existence of high-energy ion acceleration. Unfortunately, none of these configurations produce HPM of higher efficiency than a regular gridded vircator.