Klystron Station For The Advanced Free Electron Laser

This paper describes a 1300 MHz klystron and modulator system recently constructed for the Advanced Free Electron Laser (AFEL) project at Los Alamos National Laboratory. The AFEL is a very compact high power FEL. The new RF system was developed to supply up to 30 megawatts peak power, 30 microsecond pulse width and up to 100 hertz repetition rate. The average RF output power goal is 50 kilowatts. The fifty kilowatts will allow the FEL to produce at least 1 kilowatt of infrared light output. The key feature of an FEL RF system is phase and amplitude stability. The modulator is a thyratron-switched line-type design. The major goals of the modulator are reasonably compact size and automated operation. One notable feature is the use of five large switching power supplies in parallel to charge the pulse forming network. These supplies are a major contributor to the compact size of the modulator. The design of the modulator will be discussed along with the techniques employed to achieve stability, compact size, and automated operation. Modulator and RF performance wiil be described.