Suppression of Heavy Ion Generation in a Vacuum Diode with a Passive Anode

• Published in: Plasma physics reports 2022-11, Vol.48 (11), p.1244-1250
• Main Authors: Pushkarev, A. I., Zhu, X. P., Egorova, Yu. I., Prima, A., Polisadov, S. S., Lei, M. K.
• Format: Article
• Language: English
• Subjects: Anodes; Atomic; Electric fields; Electrode materials; Emission; Heavy ions; Ion beams; Ion currents; Light ions; Molecular; Nitrogen ions; Optical and Plasma Physics; Penetration depth; Physics; Physics and Astronomy; Plasma; Plasma Diagnostics; Pulse duration; Stainless steels; Thickness
• ISSN: 1063-780X; 1562-6938
• DOI: 10.1134/S1063780X22700350

— The results of the simulation and experimental study of the high-power ion beam generation in an ion diode with a passive anode (accelerating voltage of 250–300 kV, pulse duration of 150 ns, beam energy per pulse of ≈50 J) are presented. The studies were carried out on a diode with a stainless steel anode during operation in the mode of double pulses of different polarities and plasma formation at explosive emission of electrons during the first pulse. It is found that a diode with a metal anode generates nitrogen ions, and the content of heavier ions of the anode material (Fe + ) is insignificant. It is shown that the suppression of the heavy ion generation in an ion diode with a passive anode is caused by a higher expansion rate of the light-ion component of the anode plasma. The penetration depth of the electric field into the anode plasma is less than the layer thickness of lighter ions at its emission boundary; therefore, only light ions are emitted from the anode plasma and accelerated in the anode–cathode gap. The suppression of the heavy ion generation in a diode with a passive anode is a positive effect that provides an increase in the ion current when operating in the current limitation mode by the volume charge and a decrease in the density of impurity ions.