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Development of a High Voltage/High Frequency Switch Module based on SiC MOSFETs for applications in Accelerator Systems

In large medical devices such as computer tomographs and other accelerator systems, electrical switches are required to block high voltages up to several 10 kV at simultaneously high frequencies up to 10 MHz. On the other hand, a pulsed current with 150 A peak must be conducted as loss-free as possible in the switched on-state.

In order to ensure beam stability, it is crucial to switch cavities not only permanently using mechanical vacuum relays, but also temporarily from cycle to cycle. The solution approach consists of building a solid-state switch (SSS) without moving parts and to use SiC MOSFETs to increase the service life.

SiC MOSFETs have a higher blocking capability at the same ON-resistance due to the higher bandgap of SiC compared to Si semiconductors as well as a lower output capacitance, which is of great importance for the blocking performance. In addition, SiC semiconductors exhibit higher resistance to corpuscular radiation and X-rays, which are frequently encountered in the aforementioned systems.