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.