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| THPP119 |
Stabilization of Beam Performance due to Improvement of the Precise Temperature Regulation System of the SACLA Injector |
1131 |
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- T. Asaka, T. Hasegawa, H. Maesaka, Y. Otake, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
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The temperature of rf cavities in the SACLA injector have to be precisely controlled to generate stable electron beam for XFEL users. To maintain the rf voltage and phase in the each cavity, the temperatures of all the cavities were kept within 28±0.04˚C by controlling the cooling water temperature. AC power supply of the controller to heat the cooling water was operated at 2Hz by PWM control with alternatively tuning on and off. The correlation between beam position variation and a leakage magnetic field due to applying the heater current of an AC power supply was found out. Although the cooling water temperature was controlled less than ±40mK, the laser intensity was affected by slight temperature drift. Therefore, thermometer modules were replaced to more precise ones with 1mK resolution. A new temperature regulation system using a continuous level control with DC power supply was installed. The fast fluctuation of the magnetic field leak by the heater current due to the PWM control was removed. Consequently, the beam position jitter in an undulator section was reduced to less than one-third and the laser position variation was suppressed within 20μm.
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