Gridless IOT for accelerator applications

The klystron is the established microwave amplifier in accelerator driver applications, enjoying high power, gain and efficiency at saturation. Disadvantages are large size and reduced efficiency in the linear regime. The IOT, building on its success in the television broadcast market, is gaining wider acceptance as a compact, high efficiency alternative to the klystron for emerging accelerator applications. An integral component of the IOT input cavity is the control grid, which is positioned close to the cathode, not only to enhance the electric field for emission gating at the cathode surface, but also to limit the transit angle. The latter consideration constrains the operation of these devices to the lower frequency end of the microwave spectrum. Power is limited due to grid interception. Therefore, to fully exploit the benefits provided by density modulation, i.e., high efficiency and compact size, without the consequent frequency, power, and gain limitations, an emission gating method that does not rely on a closely spaced control grid is required. The solution is the Vector amplifier, a gridless IOT based on L-3's trajectory modulation technique. This device provides an alternative compact, low cost RF source for the ILC.