Equivalent Circuit Method of Resonant System of Magnetron With Sector-and-Slot Resonant Cavities

Abstract

In this paper, the equivalent capacitance and inductance of sector-and-slot resonant cavities are investigated theoretically by the equivalent circuit method. Thereby, the expression of the resonance frequency is obtained as a function of structure dimensions. In addition, the effects of structure dimensions on equivalent capacitance, inductance, and π-mode frequency are analyzed numerically, especially the slot width, slot length, and height. The results show that, compared with field theory, the equivalent circuit method is in more consistent with the simulation results, which verifies the validity of the equivalent circuit method. With the given structure dimensions, the equivalent capacitance increases with the increasing of slot length and height or the decreasing of slot width, while the equivalent inductance is opposite. Therefore, the change tendency of resonance frequency is determined by the relative changes of the capacitance, inductance, and coupling capacitance. This method can help to predesign and analyze resonant system of magnetrons with sector-and-slot resonant cavities efficiently.Index Terms-Equivalent circuit method, magnetron, resonant frequency, sector-and-slot resonant cavities.

Parameter Optimization of Hole-Slot-Type Magnetron for Controlling Resonant Frequency of Linear Accelerator 6 MeV by Reverse Engineering Technique

“…The capacitance value is considered the electric distribution required to calculate the maximum electrical voltage change occurring on the adjacent anode block to the point at the voltage as zero or the upper area of the resonant cavity. This is expressed in Equations (8) and (9). For the inductance equation, it analyzes the area of the resonant cavity that is equivalent to the magnetic field in the conductor coil where the current flows in a closed loop.…”

“…In the 1950s, a magnetron adapted for use in photon beam radiotherapy was developed which requires a pulsed RF source to accelerate electrons in the cavities of LINAC [7]. The different physical structures of the anode block in a magnetron are sector, hole-slot, rising sun, ellipse and vane-type [8][9][10]. The applied voltage between the anode and cathode in the magnetron-producing DC field and the magnetic field is applied perpendicular to the electric field in the interaction space and resonant cavities in the anode block.…”