Study on the Effect of Electron Beam Quality on a Continuously Frequency-Tunable 250-GHz Gyrotron

This is the authors' abstract. We don't add key points for this paper.

The effect of the electron beam quality, including the variation of the velocity spread, the guiding center radius spread, and the pitch factor when the operating frequency of a 250-GHz TE52mode continuously frequency-tunable gyrotron used for dynamic nuclear polarization (DNP) enhanced nuclear magnetic resonance (NMR) spectroscopy is tuned by changing the operating voltage V0or the operating magnetic field B0, on the operating frequency, the frequency-tunable range and the beam-wave interaction efficiency, has been studied based on a selfconsistent nonlinear beam-wave interaction theory. It is found that the velocity spread changes from 2.2% to 7.3% and the guiding center radius spread varies from 0.6% to 1.5%, when the operating voltage V0changes between 8 and 15 kV at an operating magnetic field of 9.24 T, the velocity spread varies from 4.1% to 6% and the guiding center radius spread changes from 0.8% to 1.4%, when the operating magnetic field B0changes between 9 and 9.3 T at an operating voltage of 10.1 kV. The variation of the velocity spread and guiding center radius spread with respect to the operating voltage or the magnetic field have a significant effect on the beam-wave interaction efficiency and the frequency-tunable range of the 250-GHz TE52mode continuously frequency-tunable DNP/NMR gyrotron,and the effect of the variation of the velocity spread and the guiding center radius spread should be taken into account in a frequency-tunable gyrotron design.