High-current electron beam generation by a metal–ceramic cathode

Abstract

We present results of the investigation of a metal–ceramic cathode suitable for technological applications. The cathode was tested in electron diodes powered by two different high-voltage generators (500 kV, 50 ns, 300 Ω, ⩽200 Hz and 300 kV, 250 ns, 84 Ω, ⩽5 Hz). The metal–ceramic cathode which was made in a form of a disk was composed of TiO2 ceramics with stainless steel spherical particles uniformly inserted inside. It was shown that already at relatively low accelerating fields (E⩽5 kV/cm) fast cathode plasma formation occurs as a result of surface flashover. This surface flashover is initiated in triple points located in micropores which were formed during the process of cathode preparation due to the different thermal expansion coefficients of the ceramic and the metal. Experimental data concerning the uniformity of the light emission from the cathode surface and inside the anode–cathode gap and divergence of the generated electron beams are presented. Also, it is shown that the uniformity of the generated electron beam depends strongly on the duration of the accelerating pulse.

Влияние Анодной И Катодной Плазмы На Работу Электронного Диода Со Взрывоэмиссионным Катодом

“…При переходе от безмасляного высокого вакуума к масляной откачке и повышении давления до 0.1 Pa катоды работают стабильнее, ресурс их работы составляет более 10 6 включений. В монографии [3] и работах [4,5] представлены результаты исследования металло-керамического катода из оксидной нанокерамики, по объему которой равномерно распределены металлические частицы. Авторы предполагают, что возникновение катодной плазмы обусловлено развитием разряда в газе в приповерхностных микропорах между диэлектриком и металлом.…”

23 GHz ferroelectric electron gun based gyrotron

“…Ferroelectric cathodes have been intensively studied in recent years, 1,2 both to define the emission physics, as well as to examine their applicability as a source for electron tubes along with other applications. 3,4 The ferroelectric cathode has several advantages over the conventional thermionic cathode, such as high current, 5,6 low cost, simple handling, a requirement of modest vacuum conditions, cold operation, and versatile shaping.…”