Study of the Ion Composition of the Diffuse Vacuum Arc on a Hot Cathode by the Time-of-Flight Method

The study of a diffuse vacuum arc (DVA) is of interest in connection with the developing methods of plasma processing of the spent nuclear fuel (SNF). This type of discharge can provide a high degree of ionization of the vapors of the cathode material in the absence of droplets and multiply charged ions. This work is devoted to the study of the ion composition of the arc discharge plasma at a consumable hot gadolinium cathode by analyzing the optical and mass spectra of ions. The plasma ion composition is determined at a discharge current of 50 A, arc voltage ranging from 4 to 14 V, and cathode temperature ranging from 1.9 to 1.95 kK. The obtained data, together with the data recorded using the condensation probe method, showed that at an arc voltage of 5 to 6 V a plasma is generated with an ionization degree close to 100%, which contains more than 95% of singly charged ions among all the charged states.