Design, fabrication and test of the klystrino

Summary form only given. The klystrino program was initiated to develop a high power RF source at W-band for tabletop accelerator, radar and communications applications. The goal of the program was to produce a 95 GHz, PPM focused, 100 kW peak power, 1% duty klystron. At W-band, both the small cavity dimensions and the required surface finish present fabrication challenges. In order to overcome these difficulties, the RF circuit for the klystrino is fabricated using an X-ray lithographic process called LIGA. The LIGA process can produce deep features (/spl les/ 3 mm) with submicron accuracy and excellent surface finish(< 50 nm). The RF design of the klystrino is straightforward with five regular cavities plus a five-gap extended interaction output cavity. The planar cross-section of the LIGA fabricated cavities requires 3-D simulation codes to model the non-axisymmetric fields. The rectangular magnets and butterfly-shaped polepieces also require a 3-D magnetostatic code to model the magnetic fields. Development of accurate 3-D simulations has been an ongoing issue in the klystrino program. The 110 kV beam voltage was chosen to make PPM focusing easier by reducing the plasma frequency. The length of the output cavity is proportional to beam velocity, so the high voltage also results in additional surface area to dissipate heat. Post-LIGA machining operations have presented the most difficult challenges to the klystrino development. Normal machining processes are pushed to the limit to achieve the one to two micron tolerances required for alignment and machining of the beam tunnel and coupling irises. Initial klystrino testing will start in February and RF performance data will be presented.