ANALYSIS OF ANODE FAILURES IN PULSED X-RAY TUBES WITH EXPLOSIVE ELECTRON EMISSION
E.I. Pal’chikov1,2, A.G. Paraskun1,2, Ya.L. Luk’yanov1
1Lavrentyev Institute of Hydrodynamics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: pulsed X-ray tube, explosive electron emission, strong electric field, high-voltage electrode failure, electron effect, plasma effect
Abstract
Various failure modes of the electrodes and insulators of pulsed X-ray tubes with explosive electron emission operating in a single-pulse flash mode are investigated. The operating parameters are as follows: capacitor bank discharge energy into the tube 30-50 J, pulse duration 40-100 ns, and electron energy incident on the anode 200-300 keV. The following experimentally observed damage types are identified: sublimation, spallation, surface melting, formation of Taylor cones drawn from the surface, droplet ejection, surface etching in the form of deep longitudinal grooves, periodic chevron-like surface patterns, deep surface cracks, micrometer-scale droplets atop Taylor cones that have traveled from the cathode to the anode, cathode bombardment by material ejected from the anode, dust-like deposition in the form of island films on the cathode and insulator, and surface flashover along the insulator accompanied by film evaporation. The mechanisms underlying the effects of high-current pulsed electron beams on the components and the influence of these damage types on the service life of the tubes are discussed.
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