Tuning Results of The Pulse Energy Doubler

The PAL-XFEL has a 716m hard X-ray linac and a soft X-ray linac. There are 51 modulators, 178 accelerators structures, and the pulse energy doublers in the linac. The construction was completed at the end of 2015. After RF-conditioned for one year in 2016, The machines provide to the user service in 30Hz, \pmb4μ s on hard x-ray. The pulse energy doubler is one of the important devices that increases the peak output power of the 2.856 GHz high frequency generated by the Klystron. The device receives a \pmb4μs length for high frequency power from the klystron and reduces the length of the pulse output to Iμs, However, the maximum peak output power can be increased four times. The total of 42 pulsed energy doublers are installed in the PAL XFEL RF system. It consists of two resonators and one 3dB coupler. The amount of heat generated depends on the operation repetition frequency. There are two ways to prevent it. Change the water temperature of the cavity cooling system or adjust the volume of each resonator. We installed a system that can remotely adjust the resonator volume by connecting a motor to each resonator. This paper reports the results of tuning at 30Hz. We also experimented a few to prepare for 60Hz operation. It reports the results of adjusting the resonance frequency by changing the volume and the cavity cooling temperature using a remote cavity tuning system.