Development of a 100 kW, 2.815 GHz Klystron

The Advanced Photon Source (APS) Short Pulse X-Ray (SBX) deflecting cavity RF system at Argonne National Laboratory (ANL) will require at least 16 10 kW CW S-band klystrons to drive 16 superconducting cavities. The present state of the art is a solenoid focused 5 kW CW with less than 50% efficiency rendering the overall efficiencies of the klystron + solenoid to less than 40% efficiency and, in addition, requiring the purchase of 16 separate DC power supplies. Calabazas Creek Research Inc. (CCR) is proposing to develop a 10 kW 2.815 GHz CW klystron that incorporates a unique time proven Periodic Permanent Magnet (PPM) focusing structure in lieu of the solenoid focusing. The final design has obtained an electronic and overall efficiency & gt;60% and eliminated the need for an expensive focusing solenoid-DC power supply combinations and substantial water cooling. Incorporation of this CW PPM focused klystron will increase the efficiency of the upgrade to the APS. All of the Phase I goals were met. A design was produced for an S-band PPM focused klystron with an output power of 13 kW at a beam voltage of 20 kV and a beam current of 1.0 A. ANL has provided a table of specifications for the required CW klystron. CCR has met all specifications and has exceeded the efficiency by 10%. Designs were realized for all of the critical components, including the electron gun, RF circuit, PPM structure, and RF input and output windows. In Phase II, because in Phase I we designed, simulated and analyzed a 100 kW CW klystron (initial specifications) and then repeated this effort for the 10 kW klystron, we will revisit our simulations of the RF interaction circuit and PPM structure toward optimizing efficiency and bandwidth. We will perform a detailed mechanical design, then fabricate, bake out and high power test this CW PPM klystron. We have budgeted for a rebuild and high power testing. In addition, we will ship the final klystron to ANL for high power testing with CCR participation. Commercial Applications and Other Benefits: This S-band CW PPM focused klystron simple geometry minimizes fabrication and power supply costs over other CW beam devices. Klystrons are used in many accelerators for research and medical applications, and for radar and communications in industry and national defense applications. In all of these applications, the S-band klystron is expected to offer a significant cost advantage.