Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
ZHANG Zhi-Gang
ZHAO Yu-Bin
XU Kai
ZHENG Xiang
LI Zheng
ZHAO Shen-Jie
CHANG Qiang
HOU Hong-Tao
MA Zhen-Yu
LUO Chen
MAO Dong-Qing
SHI Jing
WANG Yan
LIU Jian-Fei
Abstract： The low level radio frequency (LLRF) system for booster accelerator at Shanghai Synchrotron Radiation Facility (SSRF) was upgraded by a digital controller based on field programmable gate array (FPGA) technology. Parameters of voltage, frequency and field flatness in the two 5-cell cavities are controlled to meet the requirements of booster. In this article, the ramping curve of cavity voltage, amplitude and phase control loop with vector sum of the two 5-cell cavities, tuning loop and field flatness loop are analyzed and discussed in detail. A different method in tuning loop is adopted due to the limitations of ADC channels. The function realizes energy ramping of electron beam from 150 MeV to 3.5 GeV with a repetition rate of 2 Hz. With the new LLRF controller, the phase stability at ramping mode in 10 hours long operation is improved from � 1.5� (RMS) with open loop to � 0.15� (RMS) with close loop, while the detuning phase and field flatness are maintained to within � 2癮nd � 1%, respectively.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
MA Zhen-Yu
LIU Jian-Fei
HOU Hong-Tao
WANG Yan
SHI Jing
LUO Chen
FENG Zi-Qiang
MAO Dong-Qing
TANG Zheng-Bo
LI Zheng
ZHAO Shen-Jie
ZHANG Zi-Gang
ZHENG Xiang
ZHAO Yu-Bin
Abstract： Surface preparation is an important processing in production procedures of superconducting niobium cavities, deciding whether the performance of the niobium cavities can meet the specifications. A series of surface preparation methods and relevant apparatuses have been constructed at Shanghai Institute of Applied Physics (SINAP) and the standard procedures of cavity processing were established and successfully applied to different types of cavities. With standard surface preparation procedures on the 500 MHz 5-cell niobium cavity, the cavity accelerating voltage at T=4.2 K reached 7.5 MV while its quality factor was still higher than 1�109. The accelerating gradient of the IMP-HWR010 cavity reached 4.9 MV/m with the quality factor of better than 3�108 at 4.2 K.
Subjects: Nuclear Science and Technology >> Particle Accelerator submitted time 2023-06-18 Cooperative journals: 《Nuclear Science and Techniques》
TANG Zheng-Bo
MA Zhen-Yu
HOU Hong-Tao
MAO Dong-Qing
FENG Zi-Qiang
WANG Yan
XU Kai
LUO Chen
LI Zheng
SHI Jing
LIU Jian-Fei
Abstract： The 500 MHz 5-cell superconducting RF (SRF) cavity was designed aiming to be a candidate cavity for high current accelerators. A copper prototype cavity and a niobium cavity were fabricated at SINAP in 2012. In order to ensure these cavities get the desired frequency and a good field flatness higher than 98%, frequency control was implemented in the manufacturing process and pre-tuning has been done using a simple pre-tuning frame based on the bead-pull pre-tuning method. Then, TM010-π mode frequency within 5 kHz from the target frequency was achieved and the field flatness reached 98.9% on the copper prototype cavity. Finally, the same procedure was applied to the niobium cavity to obtain a field flatness better than 98% which benefited the cavity performance in the vertical testing.
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