Multi-mode tuning method for medical cyclotrons

A cyclotron and resonant frequency technology, which is applied in the direction of magnetic resonance accelerators, accelerators, electrical components, etc., can solve problems such as low time utilization efficiency, inability to realize radio frequency system tuning function, and reduced radio frequency power utilization efficiency, so as to improve the whole machine The effect of time efficiency

Active Publication Date: 2013-03-20
CHINA INSTITUTE OF ATOMIC ENERGY
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  • Abstract
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Problems solved by technology

In fact, the thermal effect of the cavity is related to the water cooling, system environment and power consumption design. When the water cooling is insufficient, the power consumption is too large, and the space heat dissipation is unfavorable, the fine-tuning capacitor board will not be able to realize the complete implementation of the RF system thermal balance process tuning function, directly The impact wil

Method used

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  • Multi-mode tuning method for medical cyclotrons

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Example Embodiment

[0019] Example 1

[0020] This medical cyclotron radio frequency low-level system tuning loop adopts multi-state tuning. After the system is powered on, the radio frequency signal changes from pulse to continuous state, and the power is increased to the required working voltage to reach the amplitude closed loop. The setting of the operating point voltage needs to be calibrated on site. When the cavity operating frequency is in resonance, adjust the operating point voltage based on the error signal as zero; the proportional integral parameters in the digital signal processor calculation also require online training. First, only the proportional parameters are used. , Set the integral parameter to zero, increase the proportional parameter until the overshoot oscillation occurs, then reduce the proportional parameter to 90%, and set the integral parameter to 0.001, based on the value of this group of parameters, optimize to ±10% best value. After the system turns into a continuo...

Example Embodiment

[0023] Example 2

[0024] The method and principle are the same as in embodiment 1, except that the timer is set to 10 minutes. In the tuning loop test on a high-current cyclotron, it was observed that the stroke of the fine-tuning capacitor plate exceeded the limit trigger signal source adjustment. The adjustment amount was 0.003MHz, the adjustment amount was sufficient for response, and the instantaneous reflection was acceptable.

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Abstract

The invention belongs to the technical field of accelerators, and discloses a multi-mode tuning method for medical cyclotrons. The method comprises that after a radio frequency system is started and turned into a continuous running state, a phase locking loop (PLL) tracking cavity resonant frequency mode is used for tuning, and a fine tuning capacitance plate is placed in the middle of an adjustment stroke; when PLL frequency update tuning operates for 5 minutes to 10 minutes, a digital signal processor controls to switch an analogue switch, the fine tuning capacitance plate is converted from position feedback to capacitance plate tuning, and simultaneously, the PLL uses a current frequency value as a starting point and a final working frequency value as an ending point, and the frequency is reduced to working frequency and fixed in a mode with 0.002 MHz of stepping and an interval of 1s; and capacitance plate position signals are monitored continuously, a stroke intermediate point serves as a reference, protection points are arranged at 4/5 positions on the left and right, and the capacitance plate is fixed after being adjusted by the PLL when surpassing the positions. According to the multi-mode tuning method for medical cyclotrons, a whole process of radio frequency starting and running can be covered completely and conveniently, and the whole machine time utilization efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of accelerators, and in particular relates to a multi-state tuning method for a medical cyclotron. Background technique [0002] The existence of the thermal effect of the RF system causes a large deviation in the resonant frequency of the cavity before and after the thermal equilibrium process. This deviation leads to a discrepancy with the theoretical design value, and the correct acceleration and extraction of the beam cannot be realized. Generally, a frequency adjustment device is added to the cavity design for dynamic tuning, and a fine-tuning capacitor plate is usually used for tuning. In fact, the thermal effect of the cavity is related to the water cooling, system environment and power consumption design. When the water cooling is insufficient, the power consumption is too large, and the space heat dissipation is unfavorable, the fine-tuning capacitor board will not be able to realize the complete i...

Claims

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Application Information

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IPC IPC(8): H05H13/00
Inventor 李鹏展殷治国张天爵纪彬赵振鲁雷钰付晓亮宋国芳
Owner CHINA INSTITUTE OF ATOMIC ENERGY
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