Abstract: SiC metal-oxide-semiconductor field-effect transistors (MOSFETs), serving as the third generation of semiconductor devices for spacecraft, must undergo anti-single event effect (SEE) radiation tests before their application. The impacts of constant and pulsed beam sources of heavy ion accelerators on SEE of SiC MOSFETs were investigated in this article. The experimental results show that the two types of beam sources have different effects on the leakage degradation of SiC MOSFETs. TCAD was used for simulating SEE of SiC MOSFETs. The simulation reveals that when two ions bombard the device at intervals of 100 ps, interaction between the two ions occurs, resulting in an enhanced electric field that may damage the gate oxide layer. Although the interaction has no significant effect on the threshold voltage for single event burnout, there is a noticeable difference in leakage degradation. This research may provide a reference for subsequent SEE experiments on SiC MOSFETs.