A magnetohydrodynamic model of a low current vacuum arc jet with a deuterium-impregnated Zr cathode

Abstract

This work investigates the characteristics of the vacuum arc jet (VAJ) with deuterium-impregnated Zr electrodes. The magnetohydrodynamic model is used considering different components including ions, electrons, and atoms. The radius of the arc root is assumed to be 1–1.5 mm, and thus, the cathode spots and the cathode spot mixing zone are not studied. The density distributions of different components are calculated to obtain the average charge number. Simulation results are discussed to analyze some experimental results. The simulation results show that atom density decreases rapidly near the cathode side. With a more focused beam, the electron temperature increases significantly, leading to more highly charged ions and a higher average charge number. Compared with pure Zr electrodes, deuterium-impregnated electrodes can emit light D ions that can increase the ion velocity and decrease the electron temperature. Therefore, the average charge number of Zr is lower. With more deuterium in the cathode, the arc voltage is lower. However, the arc column cannot change the fraction of deuterium in the VAJ, indicating that the high deuterium fraction in the experiments is caused by the deuterium emitted from the adjacent area of the cathode spots.