Electron beam generation in a diode with a gaseous plasma electron source II: Plasma source based on a hollow anode ignited by a hollow-cathode source

Abstract

We describe the operation of a hollow plasma anode (HPA) with a hollow cathode incorporated in it for the production of preliminary plasma. The operation of the hollow anode was studied with a discharge current amplitude up to 1 kA. It was shown that the gaseous discharge is realized without formation of plasma spots at the anode wall and the output grid. The plasma parameters inside the HPA were measured for different N2 gas pressures and discharge current amplitudes. It was found that the plasma acquires a positive potential with respect to the anode and that the plasma density and temperature are ⩽5×1012 cm−3 and ⩽10 eV, respectively. This plasma source was used as a cathode in a diode for the generation of high-current electron beams under an accelerating-voltage ⩽250 kV and 400 ns pulse duration. The characteristics of the diode and the generated electron beam as a function of the HPA parameters are presented. It was found that at the beginning of the accelerating pulse the diode operates in a plasma prefilled mode, and further in the accelerating pulse the diode current is determined by the emission capability of the HPA. It was shown that this source allows reliable generation of a uniform electron beam with a cross-sectional area of 100 cm2 and a current amplitude up to 1 kA without the formation of explosive plasma at the HPA output grid.