Author: Chang, M.H.
Paper Title Page
MOPVA098 Strategy Towards Non-Interrupted Operation of Superconducting Radio Frequency Modules at NSRRC 1088
 
  • Ch. Wang, F.Y. Chang, L.-H. Chang, M.H. Chang, J. Chen, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  Two modern 3rd generation light sources, the well-developed 1.5-GeV Taiwan Light Source (TLS) and the new constructed 3-GeV Taiwan Photon Source (TPS), are now in routine operation. Both storage rings are powered by the superconducting RF (cavity) modules, one CESR-type SRF module for the TLS since 2005 and two KEKB-type SRF modules for the TPS since 2014. Thanks to continuous efforts, the operational reliability of SRF modules at NSRRC is now compatible or better in comparison with the best operation record of room temperature cavities ever achieved at TLS (1992-2004). How to improve the long term availability but hold the achieved reliability of SRF modules such as to maximize the available annual user beam time, especially, under requirements on high RF power operation, become a new operational challenge, especially for the SRF modules at TPS which is now routinely operated with a forward RF power around 150-kW individually and expected to push to 300-kW in the coming future. Here we report our strategy and achievement to minimize long term interrupt of SRF operation owing to regular full-thermal cycling and annual maintenance of cryogenic plant.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA098  
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MOPVA099 The Study of Electromagnet Compensated High Power Ferrite Circulator Operation With Superconducting RF Cavity 1091
 
  • T.-C. Yu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, M.H. Tsai, Ch. Wang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
 
  In a high power RF system for accelerator application, the circulator is very important for protecting klystron or IOT from damage due to high reflection power from the cavity. When there is no beam current passing through the superconducting RF cavity of the accelerator, almost 100% RF power will be reflected from the cavity even the cavity is on resonance. The circulator shall be able to forward the reflected power to the load and remain good matching and isolation condition between ports at klystron and the cavity. However, for a ferrite material based circulator, the magnetic field within circulator would be temperature dependent which would cause the variation of input return loss and isolation between ports. Additional DC current driving electromagnet field is thus re-quired for compensating the temperature variation. Even with the compensating DC current, the circulator is still not ideal for practical operation especially when the performance of the circulator is strongly phase dependent. The phenomenon observed in actual operation with one set of SRF systems in NSRRC is thus reported in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA099  
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TUPIK107 Upgrade of the Existing PID Controller and Oxygen Detection Alarm System for SRF Modules Operating in the Taiwan Light Source 1968
 
  • F.-T. Chung, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  A Cornell-type superconducting RF cavity module was installed in the Taiwan Light Source (TLS) in 2004. New control electronics for the existing SRF modules have been designed, based on the original designs. In addition to the functions for operation, this SRF electronics system in the TLS also provides protection for the SRF modules and cryogenic system. This paper presents the SRF electronics modifications, which will enhance machine protection and make it easy to adjust and optimize operational parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK107  
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THPAB148 DIGITAL LOW LEVEL RF CONTROL SYSTEM FOR THE TAIWAN PHOTON SOURCE 4077
 
  • F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) is a 3 GeV, 500 mA, 499.65 MHz, 3rd generation synchrotron light source at NSRRC. To achieve the requirements of system flexibil-ity, fault diagnosis, precise control and high noise reduc-tion, a digital low level RF (DLLRF) control system based on Field Programmable Gate Array (FPGA) was developed. The communication interface is based on Raspberry Pi. The feedback loop performance of the control system was tested on the booster of the Taiwan Photon Source (TPS) with 950 kV gap voltage.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB148  
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THPAB150 Input Output Controller of Digital Low Level RF System in NSRRC 4083
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
 
  Low Level Radio Frequency (LLRF) systems operating at NSRRC are based on analog technology and are used both at the Taiwan Light Source and the Taiwan Photon Source. In order to have better RF field stability, a new digital LLRF system based on Field Programmable Gate Array (FPGA) was developed. A card-sized single-board computer is used as the input/output controller of the digital LLRF system and its design and implementation with EPICS applications are reported here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB150  
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THPIK101 Quarter Wavelength Combiner for an 8.5kW Solid-State Amplifier and Conceptual Study of Hybrid Combiners 4324
 
  • T.-C. Yu, F.Y. Chang, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Z.K. Liu, C.H. Lo, C.L. Tsai, Ch. Wang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
 
  Experimental results to combine ten 900 W solid-state amplifier modules based on typical quarter wavelength 10-way combiners are described for a total of 8.5 kW RF power output at 500 MHz. The power gain and phase distribution among the ten modules are measured and calculated to sense the combination efficiency. The combination efficiency of 100 modules differing in power gain and phase distribution is theoretically analysed. Groups of 5, 10, 25, 50 and 100 units are used in 4, 3, 2, and 1-stage power combination for total 100 units and the characteristics are calculated and investigated, including bandwidth, efficiency and even redundancy under various output VSWR levels. To simplify combining complexity and to eliminate the drawbacks of single stage combiners, a multi-way 2-stage coaxial to waveguide combiner is thus proposed as an expandable power combiner.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK101  
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