Magnetron injection gun for a broadband gyrotron backward-wave oscillator

C. P. Yuan, T. H. Chang, N. C. Chen, Y. S. Yeh
2009 Physics of Plasmas  
The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator ͑gyro-BWO͒. However, the velocity ratio ͑␣͒ varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions.
more » ... retical results obtained by employing a two-dimensional electron gun code ͑EGUN͒ demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code ͑computer simulation technology, CST͒. The underlying physics for constant ␣ will be discussed in depth.
doi:10.1063/1.3187903 fatcat:yagg2idwo5bethxd5qjw73z6ny