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RISS 인기검색어
- 검색키워드
- 저자 : Chao Chujie (검색결과 2 건)
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Design and performance of the digital LLRF control system for isotope production cyclotron
Chao Chujie,Chen Gen,Mao Yuzhou,Chen Yonghua,Ding Kaizhong,Zhang Xin 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.2
The project of a 14 MeV cyclotron used for isotope production was developed by ASIPP (Hefei, China). To generate stable radionuclides by the cyclotron, the beam parameters should be stabilized rigorously. Therefore, a digital low-level RF system (LLRF) was designed and built to stabilize acceleration voltage and control the resonance of the cyclotron. The system can be confgured to use Non-IQ sampling techniques, resulting in a high performance RF control without the need of very high speed acquisition hardware. In this paper, the functional requirements of LLRF systems are analyzed, including the two feedback control loops, contain tuning loop, the amplitude loop, and the automatic conditioning process. Meanwhile, the hardware design of the FPGA-based core processing board is presented. In experiments, the automatic conditioning process was tested, which certifes the process can greatly shorten the conditioning time. The stability of the cavity voltage and control efect for the resonant frequency has also been measured, and the results show that the amplitude stability is better than 0.0092% under beam loading operation. Experimental results in diferent operating modes prove that the digital LLRF system can meet the demands of RF control systems for isotope production cyclotron.
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Feedback control of thermal frequency drift for a normal conducting cyclotron under CW operation
Chao Chujie,Chen Gen,Mao Yuzhou,Chen Yonghua,Zhang Xin 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.83 No.7
A normal conducting cyclotron is developed for medical purposes, which consists of the magnet, RF cavity, ion source, vacuum system, cooling system and control system. Especially, the RF cavity, which establishes an electric feld to accelerate charged particles, is one of the most critical and complex components in an cyclotron. During long-term continuous wave (CW) operation of the cavity, there will be a rise in temperature in the RF cavity due to its own thermal loss. This can lead to mechanical deformation and frequency deviation of the cavity, and thereby having a negative impact on its performance. That is, it will increase the refected power, lower the beam current, and cause instability in the cyclotron's operation. Therefore, based on the results of multi-physics analysis, which indicated that the frequency deviation is caused by thermal loss, an automatic frequency feedback control system was designed. In addition, a CW(25 kW) operation was tested, the results displayed that the maximum refected power decreased from 729 to 70 W, and the maximum detuning phase decreased from 12.26° to 1.9° by applying the feedback control system. The frequency of the cavity shifted approximately −22.8 kHz. The experimental results demonstrate that the frequency feedback control system is efective in compensating for frequency deviation caused by thermal loss.
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