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Method and device for protecting cavity ignition of medical circular accelerator

A cyclotron and cavity technology, applied to magnetic resonance accelerators, accelerators, electrical components, etc., can solve problems such as risk, high cost, and process inversion, and achieve high safety effects

Active Publication Date: 2013-04-03
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in actual operation, the cavity will inevitably be exposed to the atmospheric environment during the process of opening the accelerator, debugging and maintenance, and the cavity will re-adsorb water vapor impurities, resulting in an inversion of the processing process.
[0004] The traditional processing method of cavity ignition protection can be processed at two power levels of high power and small signal. The former is realized by adding a first-stage circulator between the transmitter and the cavity, and the cost is very high; the latter is generally cut off by hardware Radio frequency excitation is realized, but there is only one level of protection, and there are security risks

Method used

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  • Method and device for protecting cavity ignition of medical circular accelerator
  • Method and device for protecting cavity ignition of medical circular accelerator
  • Method and device for protecting cavity ignition of medical circular accelerator

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Taking a medical cyclotron as an example, the actual operation power of the accelerator is about 16kW, including cavity loss of 14.6kW and beam power of 1.4kW. The cavity sampling coupling degree is -50.6dB, then the cavity sampling is 3.92Vpp (the line loss is 5.2dB). The chamber is driven by radio frequency pulses with a duty ratio of 1:10 and a period of 10ms. The characteristic time constant of the chamber is measured to be 14us. If the energy release rate in the chamber is greater than 3.92Vpp / 14us, ignition will occur.

[0035] Use the Agilent E4421B signal source AM modulation mode to simulate the firing rate of the cavity, and calibrate the specific value of the negative level to -0.1746V, so that the cavity sampling is differentiated and compared with the negative level to generate a narrow pulse signal during ignition, and use this narrow pulse The falling edge triggers the timer to generate a high-level monostable pulse output with a Tw of 1ms. When the radio...

Embodiment 2

[0038] The device used for the ignition protection of the medical cyclotron cavity mainly includes a cavity signal monitoring module, a pulse shaping module and a main control processing unit module, such as image 3 shown.

[0039] The cavity signal monitoring module samples and processes the cavity, identifies the ignition signal, and outputs the obtained ignition signal to the pulse shaping module, which processes the ignition signal to generate a monostable signal with a pulse width of Tw or Digital quantity, respectively used for RF switch hardware protection and main control processing unit software protection. Adjust the filter time constant T of the pulse shaping module so that T is greater than Tw, which can form a pseudo-continuous state of the cavity signal during the shutdown of the radio frequency signal, and directly restart to the continuous state after the signal is turned off to realize software protection. Signal recovery after ignition. When the hardware s...

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Abstract

The invention belongs to the technical field of accelerators and discloses a method and a device for protecting cavity ignition of a medical circular accelerator. The method includes adopting two-stage hardware and software redundancy protection, and is simple, effective and capable of restoring radio-frequency signals. The device for protecting cavity ignition of the medical circular accelerator mainly comprises a cavity signal monitoring module, a pulse shaping module and a master control processing unit module, wherein the cavity signal monitoring module is used for sampling and processing a cavity and identifying ignition signals; the pulse shaping module is used for processing the ignition signals, generating monostable signal with Tw pulse width or digital quantity which can be respectively used for protecting radio-frequency switch hardware and software of the master control processing unit. The device for protecting cavity ignition of the medical circular accelerator can be used for quickly realizing ignition protection and restoration.

Description

technical field [0001] The invention belongs to the technical field of accelerators, and in particular relates to a method for protecting a cavity of a medical cyclotron and a device used therefor. Background technique [0002] Under the excitation of the radio frequency electric field, the local vacuum deterioration of the main vacuum chamber caused by the fouling and vaporization of the cyclotron radio frequency cavity surface and the existence of microscopic protrusions on the cavity surface may cause sparking phenomenon, which causes excessive instantaneous reflection of radio frequency power , forming an impact on the transmitter, and the high-energy release during ignition will destroy the cavity structure and affect the safe and stable operation of the accelerator system. [0003] Generally, cavity surface pretreatment and cavity tempering will be carried out before official operation to reduce the possibility of cavity ignition. However, in actual operation, the cav...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05H7/02H05H13/00
Inventor 殷治国李鹏展张天爵纪彬赵振鲁雷钰付晓亮宋国芳
Owner CHINA INSTITUTE OF ATOMIC ENERGY