Variation of electron beam quality in a Continuously Frequency-Tunable 500GHz Gyrotron

The variation of the electron beam quality including the velocity spread, the guiding center radius spread, and the pitch factor when the operating frequency of a 500 GHz TE
₈₅
mode continuously frequency-tunable gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy is tuned by changing the operating magnetic field B
₀
, has been studied. It is found that the velocity spread varies from 4.7% to 5.8% and the guiding center radius spread changes from 2.09% to 2.15%, when the operating magnetic field Bo changes between 9.12 T and 9.20 T at an operating voltage of 12kV.