Abstract
Low-voltage compact gyrotron is under development at the University of Electronic Science and Technology of China (UESTC) for industrial applications. Due to the low operating voltage, the relativistic factor is weak, and interaction efficiency could not be high. Therefore, a magnetron-injection gun (MIG) with an extremely high-velocity ratio α (around 2.5) is selected to improve the interaction efficiency. As beam voltage drops, space charge effects become more and more obvious, thus a more detailed analysis of velocity-ratio α is significant to perform low-voltage gyrotrons, including beam voltage, beam current, modulating voltage, depression voltage, cathode magnetic field, and magnetic depression ratio. Theoretical analysis and simulation optimization are adopted to demonstrate the feasibility of an ultra-high velocity ratio, which considers the space charge effects. Based on theoretical analysis, an electron gun with a transverse to longitudinal velocity ratio 2.55 and velocity spread 9.3% is designed through simulation optimization. The working voltage and current are 10 kV and 0.46 A with cathode emission density 1 A/cm2 for a 75 GHz hundreds of watts’ output power gyrotron.
Highlights
Gyrotron is a kind of vacuum electronic device, of which the operation is based on the stimulated cyclotron radiation of electrons oscillating in a strong magnetic field
A higher α will cause the limit current to decrease, and when the operating current is close to the limit current, it will cause the reversal of the electron beam, which drastically affects the emission and interaction efficiency
The purpose of the current study was to determine the feasibility of the ultra-high velocity ratio of magnetron-injection gun (MIG) for low-voltage gyrotron
Summary
Gyrotron is a kind of vacuum electronic device, of which the operation is based on the stimulated cyclotron radiation of electrons oscillating in a strong magnetic field. As the above principle of stimulated cyclotron radiation, the electrons energy can be transferred to the fast-wave in the interaction circuit It can be operated at high-order mode in the cavity, the dimensions of the Electronics 2020, 9, 1587; doi:10.3390/electronics9101587 www.mdpi.com/journal/electronics. The process of the gyrotron is mainly between is mainly between the transverse electron cyclotron velocity and the perpendicular electric the transverse electron cyclotron velocity and the perpendicular electric field, so increasingfield, the so increasing can directly improve the interaction and becomes a key velocity ratio the canvelocity directlyratio improve the interaction efficiency andefficiency becomes a key method to method to theofefficiency of the low-voltage gyrotron. The present development status of low(less than 10 than kV) gyrotron improves the efficiency by increasing the pitchthe factor within velocity voltage
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