Development of a High Gain, High Power Traveling Wave Relativistic Klystron

75016-Relativistic klystrons that are presently under development for linear collider applications, as well as existing high-power pulsed klystrons that energize research linear accelerators, typically have amplification factors (gain) between 45 and 55 dB. These klystrons generally require pulsed vacuum tube drivers to supply input power levels up to several hundred watts. However, for multiple klystron linac applications, especially linear colliders, a 20 dB increase in klystron gain is needed for both cost savings and simplification ¿ because then the relatively complex vacuum tube driver systems could be replaced by small, low-power solid state sources. This project will develop technology leading to a stable, high gain (>70 dB), high power, 17 gigahertz relativistic klystron. The technology will exploit the unique space-charge controlling characteristics of an asynchronously-operated, tapered-impedance-traveling-wave output structure to provide enhanced bunching and additional gain, as radio frequency power is extracted from the decelerating electron beam with high conversion efficiency (>50 percent). Phase I will investigate the phase orbit characteristics and establish the microwave parameters for the output structure, which will be designed for high gain, high efficiency performance with a 17 gigahertz relativistic klystron. Parasitic oscillation suppression circuits will be designed for integration into the output arms of the klystron, and a detailed layout drawing of the overall assembly will be prepared to assist in the fabrication and high power testing of the klystron in Phase II. Commercial Applications and Other Benefits as described by the awardee: A stable, high gain klystron amplifier should enable existing complex driver systems and associated pulsed helix and filament power supplies to be replaced by simple, low power solid state amplifiers in accelerators for High Energy Physics research.