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Hou H.T.,CAS Shanghai Institute of Applied Physics | Liu J.F.,CAS Shanghai Institute of Applied Physics | Zhao Z.T.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology
IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference | Year: 2013

Harmonic cavity can improve the beam quality through bunch size lengthening which includes providing Landau damping, suppressing coupled bunch instability and microwave instability, enhancing the beam current per bunch besides the beam lifetime improvement. A passive third harmonic superconducting cavity operating at super fluid liquid helium has been proposed for the SSRF storage ring with compromise on the required harmonic voltage, limited installation space and dissipated cryogenic power. This paper will mainly present the conceptual design of the harmonic rf system including the requirement of SSRF, a brief review on beam dynamics of harmonic rf system and the harmonic cavity choice. Copyright © 2013 by JACoW- cc Creative Commons Attribution 3.0 (CC-BY-3.0).


Tan J.-H.,CAS Shanghai Institute of Applied Physics | Tan J.-H.,University of Chinese Academy of Sciences | Gu Q.,CAS Shanghai Institute of Applied Physics | Fang W.-C.,CAS Shanghai Institute of Applied Physics | And 3 more authors.
Nuclear Science and Techniques | Year: 2015

In this paper, we propose a two-mode polarizable deflecting structure, as a new concept for bunch measurement and beam control. With two modes of HEM11 and HEM12 operating in the same structure on horizontal and vertical directions, respectively, the operation status can be switched between the two polarization modes. They can be operated simultaneously with two independent input power sources. With two-mode deflecting structure, the bunch distortion caused by the geometric wake-fields in the accelerating structure can be measured by one structure. © 2015, Science Press. All rights reserved.


Hou H.-T.,CAS Shanghai Institute of Applied Physics | Hou H.-T.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology | Ma Z.-Y.,CAS Shanghai Institute of Applied Physics | Ma Z.-Y.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology | And 25 more authors.
Chinese Physics C | Year: 2015

A low loss- (LL) type 500 MHz 5-cell superconducting niobium prototype cavity with a large beam aperture has been developed successfully including the optimization, the deep drawing and electron beam welding, the surface treatment and the vertical testing. The performance of the fundamental mode was optimized and the higher order modes were damped by adopting an enlarged beam pipe for propagation. Surface preparation or treatment including mechanical polishing, buffered chemical polishing and high pressure rinsing with ultra-pure water and so on was carried out carefully to ensure a perfect inner surface condition. The vertical testing results show that the accelerating voltage higher than 7.5 MV was obtained while the quality factor was better than 1×09 at 4.2 K. No obvious multipacting or field emission was found during the test. However, a quench happened while increasing the field a little higher than 7.5 MV that at present limited the cavity performance. © 2015 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.


Zhang Z.-G.,CAS Shanghai Institute of Applied Physics | Zhang Z.-G.,University of Chinese Academy of Sciences | Zhang Z.-G.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology | Zhao Y.-B.,CAS Shanghai Institute of Applied Physics | And 25 more authors.
Nuclear Science and Techniques | Year: 2015

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° and ±1%, respectively. © 2015, Science Press. All rights reserved.


Zheng X.,CAS Shanghai Institute of Applied Physics | Zheng X.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology | Zhao Y.B.,CAS Shanghai Institute of Applied Physics | Zhao Y.B.,Shanghai Key Laboratory of Cryogenics and Superconducting RF Technology | And 18 more authors.
IPAC 2010 - 1st International Particle Accelerator Conference | Year: 2010

The digital low level radio frequency (DLLRF) system and the beam trip diagnostic system in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF) have been operational for more than one year. The DLLRF has successfully maintained the amplitude and phase stability of the cavity field in the superconducting cavity even when the beam current in the storage ring reached 300mA at 3.5GeV, and the beam trip diagnostic system has been realized and is helpful for improving the reliability of the RF system.

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