Automatic tuning device and method for resonant cavity of cyclotron

Abstract

The invention discloses an automatic tuning device and method for a resonant cavity of a cyclotron. The device comprises two sets of DEE plates which are oppositely arranged in an end-to-end mode; the upper side and the lower side of each set of the DEE plates are perpendicularly connected with inner rods respectively, and each inner rod is provided with a mobile tuning ring; each tuning ring is composed of an annular short circuit plate and a mobile rod, the annular short circuit plates are embedded into the corresponding inner rods, the inner sides of the annular short circuit plates electrically make contact with the corresponding inner rods, and the outer sides of the annular short circuit plates electrically make contact with the cavity wall of the resonant cavity; one end of each mobile rod is connected to the corresponding annular short circuit plate; feedback probes are connected to the portions, opposite to the inner rods, of the cavity respectively. The method comprises the steps that the resonant frequency is tuned by a vector network analyzer, a frequency point f1 corresponding to a smallest reflection coefficient S11 is measured, the tuning rings are moved, and when f1=f0, the resonant frequency point requirements are met. According to the automatic tuning device and method, the automatic cavity frequency tuning purpose is achieved, by automatically controlling the tuning rings to move up and down and changing the length of the cavity of the cyclotron, the resonant cavity works at fixed resonant frequency, and then damaged caused by detuning is avoided.

Description

technical field [0001] The invention belongs to the technical field of cyclotrons, and relates to an automatic tuning device and method for a cyclotron resonant cavity. Background technique [0002] Cyclotrons are widely used in the research fields of heavy ion biological effects, heavy ion cancer treatment, material science and single event effects of aerospace devices, especially in the fields of radiopharmaceuticals and tumor treatment. It is imperative to build a medical cyclotron with independent intellectual property rights and put it into operation smoothly. Hefei Ion Medicine Center has carried out proton therapy and other related biomedical research, and has done a lot of research and experimental work on the development of superconducting cyclotrons. [0003] As an important part of the cyclotron, the high-frequency system plays an important role in the process of particle acceleration. The system mainly includes a high-power radio frequency source and a resonant ...

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Problems solved by technology

[0004] In actual operation, the physical deformation caused by the loss and heat of the cavity leads to changes in the resonant frequency of the resonant cavity. Although it is water-cooled to prevent thermal deformation of the cavity, the cooling water cycle will cause mechanical vibration of the cavity, plus other The mechanical vibration of the cavity caused by various equipment, these factors will cause the cavity to be detuned

Slight detuning will cause the reduction of high-frequency voltage and the drift of high-frequency signal phase, which will cause loss to the ion beam current of the accelerator. Excessive detuning will cause a mismatch between the high-frequency transmitter and the high-frequency cavity, causing If the high-frequency reflection power is too large, the high-frequency power cannot be completely transmitted to the resonant cavity, but is reflected to other weak links, causing high-frequency power self-excited oscillation, and in severe cases, causing damage to the high-frequency power source, or causing shocks inside the high-frequency feeder. Wear discharge, or even burn some high-frequency feeders

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