10 MW Annular Beam Klystron for Accelerators

Advanced high power microwave sources are required for future high energy accelerators. Typical requirements are 10 MW pulses with 65% efficiency and a beam voltage of 120 kV or lower. This implies a beam purveyance of about 4 micropervs. With this purveyance, it is impossible to achieve the required efficiency with a conventional klystron. Calabazas Creek Research Inc. is developing a 10 MW, 1.3 GHz annular beam klystron (ABK). The ABK uses an annular beam to reduce space charge depression and reduce the operating voltage. The ABK will achieve similar performance as multiple beam klystrons, but at significantly lower cost. The program will demonstrate a major advance in high power klystrons that will be applicable to a wide range of frequencies and powers. A previous program developed preliminary design that achieved the required specifications. This Phase I program focused on verification that beam instabilities would not prevent successful operation. Extensive analysis and computer simulations indicate the ABK should be absolutely stable and provide the required performance. The ABK design will be finalized and a full power device will be built and tested. The design will be further modified to improve performance and reduce cost. Commercial Applications and Other Benefits: The ABKs relatively simple geometry will reduce fabrication costs while providing equivalent performance to multiple beam devices. Klystrons are used in accelerators for research and medical applications, and for radar and communications and the defense systems. The ABK offers a significant cost advantage over competing RF sources, currently produced in Europe and Japan. This would reestablish the U.S. as the leader in higher power RF sources for accelerators and similar systems.