Advanced high-power microwave vacuum electron device development

The microwave power requirements of particle accelerators have been growing almost exponentially during the last three decades. As a result, economic necessities have been driving the development of microwave vacuum electron devices into three: (i) maximizing the power handling capability of any single device; (ii) maximizing its overall efficiency; (iii) minimizing its manufacturing costs. This process has sparked a research into a multitude of new devices, as for instance magnicons, relativistic klystrons, super-reltrons and others. The field, however, is still dominated by the classic single-beam klystron, in both its super-power continuous wave and pulsed versions. Power capability and inherent reliability still make it the prime candidate for the majority of currently planned accelerators. Development efforts are therefore directed into further improving its efficiency, but mainly into reducing its costs. Distributed-beam devices, such as the multi-beam klystron (MBK) and the higher-order mode inductive-output tube (HOM-IOT) share a number of properties with the single-beam klystron, but offer the added advantages provided by lower beam voltage