Influence of thermionic emission on the current–voltage characteristics of a hot target magnetron

This study investigates the impact of the lateral distribution of surface temperature on the current–voltage characteristics (I–V characteristics) of a balanced magnetron hot target. The study is based on the analysis of the results obtained from measuring the I–V characteristics of a balanced magnetron with a diameter of 130 mm, featuring a hot titanium target sputtered in an inert environment. It was observed that, regardless of the working gas pressure, an increase in current leads to a transition of the discharge into the arc stage. The reason for this effect is an increase in thermionic emission to a significant level. A differential technique was used to model the emission process. It is based on the established distribution of the target's surface temperature, for which numerical evaluation was conducted using the Heat Transfer Module of the COMSOL Multiphysics. This work relates to fundamental studies of a dc gas discharge with a hot cathode on which a magnetic field is imposed. The results obtained can be applied practically in the development of technologies for depositing films of metals and their alloys.