Author: Huang, G.
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MOPMY016 Quadrature Directional Coupling Method for Precise RF Power Measurement 549
SUPSS096   use link to see paper's listing under its alternate paper code  
  • B. Du, G. Huang, L. Lin, Y.T. Liu, Z. Zhao
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The directional coupler is used in the RF transmission and distribution system of accelerator, to measure the forward and backward power. Due to the finite directional isolation of the coupler (20-30dB normally), the crosstalk exists between the bi-directional coupling output signals. For the typical isolation of 26dB, if the bi-directional crosstalk signals are in- or anti- phase, the error of input or reflected power measurement is 10% in case of total reflection, whilst the error of reflected power measurement is 100% in case of VSWR 1.1. A method of quadrature directional coupling measurement is developed to solve the isolation problem. A pair of directional couplers with 90° phase difference are employed to measure the RF power. The influence of the directional crosstalk would be reduced significantly by processing the measurement data. The prototype of quadrature directional couplers is constructed to verify this method. The results showed that the measurement accuracy of quadrature coupler pair after data process is better than 2% for forward measurement, even if the error of single coupler is over 6%. The paper also analyses the error caused by non-ideal quadrature.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY016  
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MOPOW054 The 4th Harmonic Cavity for Hefei Light Source-II 837
  • C.-F. Wu, S. Dong, G. Huang, D. Jia, K. Jin, C. Li, J.Y. Li, W. Li, J.G. Wang, L. Wang, W. Xu, K. Xuan
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • R.A. Bosch
    UW-Madison/SRC, Madison, Wisconsin, USA
  • G.Y. Kurkin, E. Rotov
    BINP SB RAS, Novosibirsk, Russia
  • G. Ya
    Budker Institute of Nuclear Physics, Novosibirsk, Russia
  The 4th harmonic cavity has been firstly used in the storage ring for HLS-II. The paper presents the physics design, developing process and the experimental results for commision. The measurment results show that rf parameters are reasonable. The 4th harmonic cavity efficiently lengthen the bunch and increase the beam life-time. Specially, the beam instablity has been supressed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW054  
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WEPOY002 A Time Domain Analysis Method for RF Noise 2994
  • L. Lin, B. Du, G. Huang, Y.T. Liu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  A time domain analysis method is developed for the calculation of the longitudinal oscillations caused by the RF noise in the storage ring. This method is based on the impulse response model, and it could calculates the change of transient field caused by beam oscillation and RF noise turn by turn. By means of discrete spectrum analysis, the spectrum of the beam is obtained. According to this analysis method, we developed a simulation pro-gram. The synchronous oscillation of the excited by high RF source with a phase modulation is predicted in this program, and the corresponding experimental measure-ments are carried out on HLS II. The fitting results are in agreed with the experimental measurements.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY002  
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THPOY028 Operational Status of HLS-II 4155
  • J.Y. Li, G. Huang, W. Wei, W. Xu, K. Xuan, Y.L. Yang, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  After a major renovation, the Hefei light source (HLS), renamed HLSII, was brought into operation in the beginning of 2015. The operational result shows that the HLS-II not only provides much brighter synchrotron radiation beam for various users, but also shows much higher reliability than the old light source. This paper first gives an overview of the HLS-II. The overall performance of the light source is then summarized in this paper. Some measured key parameters of the light source, including emittance, orbit stability, beam lifetime and so on, are also presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY028  
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