Erosion of Electrodes in a Three-Electrode Pulsed X-Ray Tube with Explosive Emission

Erosion of electrodes in a three-electrode pulsed X-ray tube with a rechargeable insulated electrode operating in the explosive emission mode at a voltage of 600 kV and pulsed current up to 1000 A was investigated. Erosion was produced by the action of high pulsed electric fields and pulsed flows of electrons and plasma during vacuum breakdown in X-ray tubes. X-ray fluorescence microanalysis using a scanning microscope revealed the presence of numerous metal balls of size 10–40 $$\mu $$ m formed from both the tungsten anode material and the material of the third insulated Kovar electrode. Several stages of detachment of the balls by the electric field were detected on the insulated electrode. The critical values of the Coulomb forces at which droplets arise in accordance with a dynamic model (taking into account the kinetic energy accumulated by the mass during the time of exposure to the electric field and surface energy) and the electric field pressures during the operation of the tube were estimated, allowing an explanation of the observed phenomena.