Development of 30 MW L-band pulse klystron for XFEL

An L-band pulse klystron E37612 was developed as a high power RF source for the L-band standing wave type accelerating structure in the X-ray Free Electron Laser (XFEL) under construction at SPring-8. The klystron E37612 can output 30 MW peak power with frequency of 1428 MHz. We designed the klystron based on the design of the 50 MW C-band klystron and the 50 MW S-band klystron by using the simulation code FCI . The first tube was manufactured and tested at Toshiba Electron Tubes and Devices Co,. Ltd. in January, 2010. The klystron shows good characteristics up to the ratings operation. Since some instability phenomena were seen in the area of the low beam voltage, we optimized the current of the focusing magnet to suppress the instability. (author)