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Measurement of the cavity-loaded quality factor in superconducting radio-frequency systems with mismatched source impedance
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作者 jin-ying ma Cheng-Ye Xu +12 位作者 An-Dong Wu Guo-Dong Jiang Yue Tao Zong-Heng Xue Long-Bo Shi Tian-Cai Jiang Zheng-Long Zhu Zi-Qin Yang Zheng Gao Lie-Peng Sun Gui-Rong Huang Feng Qiu Yuan He 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2023年第8期12-23,共12页
The accurate measurement of parameters such as the cavity-loaded quality factor(Q_(L))and half bandwidth(f_(0.5))is essential for monitoring the performance of superconducting radio-frequency cavities.However,the conv... The accurate measurement of parameters such as the cavity-loaded quality factor(Q_(L))and half bandwidth(f_(0.5))is essential for monitoring the performance of superconducting radio-frequency cavities.However,the conventional"field decay method"employed to calibrate these values requires the cavity to satisfy a"zero-input"condition.This can be challenging when the source impedance is mismatched and produce nonzero forward signals(V_(f))that significantly affect the measurement accuracy.To address this limitation,we developed a modified version of the"field decay method"based on the cavity differential equation.The proposed approach enables the precise calibration of f_(0.5) even under mismatch conditions.We tested the proposed approach on the SRF cavities of the Chinese Accelerator-Driven System Front-End Demo Superconducting Linac and compared the results with those obtained from a network analyzer.The two sets of results were consistent,indicating the usefulness of the proposed approach. 展开更多
关键词 Loaded quality factor Field decay method Superconducting cavity MISMATCH Calibration Cavity differential equation Measurement Accelerator-driven system
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Precise calibration of cavity forward and reflected signals using low-level radio-frequency system 被引量:1
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作者 jin-ying ma Feng Qiu +11 位作者 Long-Bo Shi Zheng-Long Zhu Tian-Cai Jiang Zong-Heng Xue Ke-An Jin Qi Chen Cheng-Ye Xu Xing-Hao Ding Zheng Gao Lie-Peng Sun Gui-Rong Huang Yuan He 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第1期35-43,共9页
Precise measurements of the cavity forward(Vf)and reflected signals(Vr)are essential for characterizing other key parameters such as the cavity detuning and forward power.In practice,it is challenging to measure V_(f)... Precise measurements of the cavity forward(Vf)and reflected signals(Vr)are essential for characterizing other key parameters such as the cavity detuning and forward power.In practice,it is challenging to measure V_(f) and V_(r) precisely because of cross talk between the forward and reflected channels(e.g.,coupling between the cavity reflected and forward signals in a directional coupler with limited directivity).For DESY,a method based on the cavity differential equation was proposed to precisely calibrate the actual V_(f) and V_(r).In this study,we verified the validity and practicability of this approach for the Chinese ADS front-end demo superconducting linac(CAFe)facility at the Institute of Modern Physics and a compact energy recovery linac(cERL)test machine at KEK.At the CAFe facility,we successfully calibrated the actual V_(f) signal using this method.The result demonstrated that the directivity of directional couplers might seriously affect the accuracy of V_(f) measurement.At the cERL facility,we calibrated the Lorentz force detuning(LFD)using the actual Vf.Our study confirmed that the precise calibration of V_(f) significantly improves the accuracy of the cavity LFD measurement. 展开更多
关键词 Forward and reflected signals MEASUREMENT CALIBRATION
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In situ mitigation strategies for field emission-induced cavity faults using low-level radiofrequency system
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作者 Feng Qiu Yuan He +10 位作者 An-Dong Wu Zhen-Long Zhu Guo-Dong Jiang Tian-Cai Jiang Zheng Gao Qi Chen Zong-Heng Xue jin-ying ma Cheng-Ye Xu Zi-Qin Yang Gui-Rong Huang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2022年第11期46-60,共15页
In the Chinese ADS front-end demo superconducting radiofrequency linac(CAFe)at the Institute of Modern Physics,a burst-noise signal-triggered cavity fault frequently appears during beam commissioning.These events are ... In the Chinese ADS front-end demo superconducting radiofrequency linac(CAFe)at the Institute of Modern Physics,a burst-noise signal-triggered cavity fault frequently appears during beam commissioning.These events are characterized by a rapid burst noise in the cavity pick-up,which may lead to an unexpected low-level radiofrequency(LLRF)response that eventually causes a cavity fault.To eliminate the undesirable reaction of the LLRF control loop,we propose a method that uses a burstnoise detection and processing algorithm integrated into the LLRF feedback controller.This algorithm can prevent undesired regulations in LLRF systems.Data analysis revealed that some burst-noise events did not exhibit measurable energy loss.In contrast,the other events were accompanied by a rapid loss of cavity stored energy and exhibited similarities to the‘‘E-quench’’phenomena reported in other laboratories.A particle-in-cell simulation indicated that the suspected E-quench phenomenon may be related to a plasma formation process inside the cavity.Fortunately,the LLRF algorithm is robust to the two different types of burst-noise events and can significantly mitigate the corresponding cavity faults in CAFe beam commissioning. 展开更多
关键词 Field emission FLASHOVER E-quench Superconducting LLRF CAFE Plasma formation
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