X-Band Amplifier for the PAL-XFEL

Recent X-ray free electron lasers based on a high-energy high-current linear accelerator, such as the Pohang Accelerator Laboratory (PAL-XFEL) uses a third harmonic radio-frequency (RF) linearizer system to improve the laser's longitudinal beam quality. Because the X-ray free electron laser at the PAL-Xfel uses 2856 MHz RF accelerators, we realized a RF linearizer of 11.424 GHz which afforded a 50 MW RF power by using a SLAC X-band klystron. Operation of the X-band klystron required an X-band amplifier with a 1 kW level at the specified frequency of 11.424 GHz. We tested two types of X-band amplifier, a traveling wave tube amplifier and a solid state amplifier. In this work, we present the test results and discuss the features, especially focusing on the X-band solid state amplifier.