DEPENDENCE OF CATHODE APERTURE IN PULSED HOLLOW-CATHODE DISCHARGES

The effect of electric field penetration in the hollow-cathode region of self-initiated pulsed hollow-cathode discharge is investigated. The discharge is operated in hydrogen at pressures between 30 and 200 mTorr with applied voltages between 10 and 30 kV. Aluminum cathodes with aperture diameters and lengths from 1 to 5 and 2 to 18 mm, respectively, are used. The results show that the effect of the hollow cathode in discharge initiation is particularly strong at low pressures. In the range of parameters investigated, the time delay to breakdown and the jitter decrease when cathode aperture with larger diameters and shorter lengths are used. At high pressure the pulsed hollow-cathode effect is less important as ionization processes in the main gap become dominant.