Author: Tong, J.
Paper Title Page
THPRB041 Design a Precise Stability Controller for High Power Pulse Modulator Based on FPGA 3900
THPRB040   use link to see paper's listing under its alternate paper code  
 
  • Y.F. Liu, Z.H. Chen, M. Gu, J. Tong, Y. Wu, Q. Yuan, X.X. Zhou
    SINAP, Shanghai, People’s Republic of China
 
  Shanghai Soft X-ray Free Electron Laser (SXFEL) facility is under testing at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences. The stability of RF system is one of the major factors to get great beam performance. It is mainly determined by klystron modulators power supply. The beam voltage of the LINAC klystron modulator, which is the pulsed power source of the RF amplifier, is directly affecting the RF amplitude and phase. This paper shows the suitable upgrade scheme of the modulator power supply and design considerations for the stability improvement of modulator power supply for Shanghai SXFEL. We present a real time feedback control system of LINAC pulse modulator to improve pulse to pulse amplitude stability. The feedback control system is based on the principle of embedded FPGA techniques. The control system consists of an embedded NIOS II processor, a High resolution ADC and an upper computer. The NIOS II processor manage on chip FIFO, ADC, IRQ, and Ethernet. The relevant experiments indicate that the feedback control strategy reaches required function. It is useful to improve the stability of existing modulator power supply.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB041  
About • paper received ※ 21 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB042 Stability Research Progress on High-power Pulse Modulator for SXFEL-UF 3904
 
  • Q. Yuan, M. Gu, Y.F. Liu, J. Tong, Y. Wu
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Supported by the National Natural Science Foundation of China(11675250)
Abstract: SXFEL-UF(Shanghai Soft X-ray Free Electron Laser User Facility) under construction presently demands higher energy stability. Stability of pulse modulator feeding power for klystron plays an utmost important role in energy stability and occupy dominant factors in bringing influences in stability of RF power. Presently, stability of high-power pulse modulator of LINAC (Linear Accelerator) is on the level of 0.1% to 0.05% usually. In order to meet the higher stability requirements, it is very necessary for close-loop feedback control techniques instead of traditional open-loop to be applied in the modulator design. The stability controller adopts double control-loops techniques which feedback signals are respectively from PFN(Pulse Forming Network) and pulse transformer in oil tank. In addition, the paper also introduces recent progress on high stability CCPS research(Capacitor Charging Power Supply), which brings direct impact on the stability of modulator. In comparison with the former close-loop design, high stability CCPS design takes the overall modulator stability into full consideration. And the feedback control algorithm utilized to adjust PWMs for full bridge switch is implemented in the CCPS controller directly rather than modulator controller independent of CCPS. It is expected to obtain 0.01% stability by taking the above measures.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB042  
About • paper received ※ 06 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB043 Design and Simulation of Thin Eddy-Current Septum for Injection of Diffraction Limited Storage Ring 3908
 
  • J. Tong, M. Gu, B. Liu, Y.F. Liu, R. Wang
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Work supported by the National Key Research and Development Program of China(Grant No.2016YFA0402002)
Ultra-low emittance in Diffraction Limited Storage Ring (DLSR) usually has small Dynamic Aperture (DA), which makes the traditional off-axis injection inadequate. Fast kickers together with thin septum magnets or direct current lambertsons could support on-axis injection for closely-spaced bunches with small DA. Thin eddy-current septum prototype had been designed for injection with laminated silicon steel sheets as magnet core. Theoretical analysis and transient simulation had been carried out within OPERA software. Due to the minimum thickness of the septa is only 1 mm , several optimization approaches had been applied, such as shielding with strongly paramagnetic material and exciting with full cycle driving pulse, to satisfy the requirement that the leakage field is less than 0.1% with respect to the main one.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB043  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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