10 MW, L-Band Annular Beam Klystron

Advanced L-Band sources are required for the International Linear Collider (ILC). These must have a power of 10 MW at an efficiency of at least 40% while operating with a beam voltage of 120 kV or lower. This implies a beam perveance of about 4 micropervs. With this perveance, it is essentially impossible to achieve the required efficiency with a conventional klystron. Calabazas Creek Research Inc. (CCR) is proposing to develop a 10 MW, 1.3 GHz annular beam klystron (ABK). The ABK uses an annular beam to minimize space charge depression and the impedance, allowing the use of the low voltage required for the ILC. Like the sheet beam klystron, it uses a thin beam located close to the drift tube walls but operates with lower risk, single mode cavities. In addition, it is azimuthally symmetric, reducing design and fabrication costs. It operates at essentially the same voltage as a multi-beam klystron but is far simpler. This proposal concentrates on stability and formation of the electron beam and the efficiency of the circuit. Commercial Applications and Other Benefits: The ABKs relatively low voltage and simple geometry should minimize fabrication and power supply costs. Klystrons are used in many accelerators for research and medical applications, and for radar and communications in industry and the DoD. In all of these applications, the ABK is expected to offer a significant cost advantage