Overview of vacuum electron devices for biomedical applications

In this paper, we first introduce the high power vacuum electron devices (VEDs) such as magnetron, klystron, backward wave oscillator, traveling-wave tube, and gyrotron which can be used in the biomedical areas. And then we present the significant progress in the emerging metamaterial-inspired VEDs in our group in details and briefly address the future applications to the biomedical fields. Finally, in order to further improve the armarium's performance, we report the recent advances in the high power terahertz sources developed from the conventional VEDs and novel metamaterial VEDs.