High-quality axis-encircling electron beam is essential to drive a high-harmonic gyrotron. A magnetic cusp gun that can generate a low-spread axis-encircling electron beam at an extremely high magnetic-compression ratio was developed for a 1-THz 4th-harmonic gyrotron toward continuous-wave operation. The optimized gun could generate an axis-encircling electron beam with 80-kV voltage, 1-A current, and a nearly constant pitch factor of about 1.5 in a wide range of magnetic field strength. The transverse velocity spread was less than 2.1% and the guiding center radius was 26.6 µm. The design was verified by using MAGIC, EGUN, and CST simulations and good agreements were achieved.
|Number of pages
|IEEE Transactions on Electron Devices
|Accepted/In press - 7 Oct 2021
- magnetic cusp gun
- axis-encircling beam
- THz gyrotron