Author: Kobayashi, T.
Paper Title Page
WEPFI017 Performance of Cavity Phase Monitor at J-PARC Linac 2738
  • K. Futatsukawa, S. Anami, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
    KEK, Ibaraki, Japan
  • F. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
  The amplitude and the phase stabilities of the RF system play an important role for the cavity of a high intensity proton accelerator. For the J-PARC Linac, the accelerating field ambiguity must be maintained within ±1% in amplitude and ±1 degree in phase due to the momentum acceptance of the next synchrotron. To realize the requirement, a digital feedback (FB) control is used in the low level RF (LLRF) control system, and a feed-forward (FF) technique is combined with the FB control for the beam loading compensation. The stability of ±0.2% in amplitude and ±0.2 degree in phase of the cavity was achieved including the beam loading in a macro pulse. Additionally, the cavity phase monitors, which can measure the phase difference between any two cavities, were installed in summer, 2011. The monitor has the three different types, which are for the present 324-MHz RF system, the 972-MHz RF system and the combined system of 324-MHz RF and 972-MHz RF. The phase monitor for the 324-MHz RF has been in operated since Dec. 2011. We would like to introduce the phase monitor and indicate the phase stability at the J-PARC linac.  
WEPME014 Progress in Development of New LLRF Control System for SuperKEKB 2953
  • T. Kobayashi, K. Akai, K. Ebihara, A. Kabe, K. Nakanishi, M. Nishiwaki, J.-I. Odagiri
    KEK, Ibaraki, Japan
  • H. Deguchi, K. Harumatsu, K. Hayashi, T. Iwaki, J. Mizuno, J. Nishio, M. Ryoshi
    Mitsubishi Electric TOKKI Systems, Amagasaki, Hyogo, Japan
  For the SuperKEKB project, a new LLRF control system was developed to realize high accuracy and flexibility. It is an FPGA-based digital RF feedback control system using 16-bit ADC's, which works on the μTCA platform. The FPGA boards control accelerating cavity fields and cavity tuning, and the EPICS-IOC is embedded in each of them. The CSS-BOY was adopted for a user interface of our system. High power test of the new LLRF control system was performed with the ARES Cavity of KEKB. The obtained feedback control stability with a klystron drive was sufficient as well as the low-level evaluation result. And auto tuner control also worded successfully. The start-up sequencer program for the cavity operation and auto-aging program also worked very well. The temperature characteristics of the system depend largely on band-pass filters (BPF). We tried to tune the BPF to reduce the temperature coefficient. Consequently the temperature dependence was improved to satisfy the required stability.