Numerical simulation research of plasma characteristics in a multi-cusp proton source based on magnets layout

Abstract

It is significant to study negative hydrogen ion source for the construction of Chinese national spallation neutron source (CSNS) and the implementation of the international thermonuclear experimental reactor (ITER) project. Numerical simulation is an indispensable research measure due to the physical characteristics of ion source. In view of the facts above, in this paper we first elaborate the self-developed three-dimensional particle-in-cell/Monte Carlo collisions (PIC/MCC) algorithm and then describe the mechanism of negative hydrogen ion (H-) volume production. Based on these, the multi-cusp proton source of the Chinese atomic energy research center is systematically simulated. In the cases of the same polarities and the opposite polarities of extraction magnetic fields, multi-cusp proton source discharge characteristics are discussed and analyzed respectively. The result shows that in the case of the opposite polarities of the two extraction magnets, magnetic drift directions near the two extraction magnets are the same and have great values, namely intense magnetic drift, which causes the total number of electrons to be big, and induces the high-energy electrons to become active in a specific area. And so, the volume production rate of H- ions is higher, that is to say, H- ions present Y drift. On the contrary, in the case of the same polarities of the two extraction magnets, the binding effect of electron is worse and the volume production rate of H- ions is lower, but spatial distribution of volume production H- is uniform.