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》
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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