A Choppertron RF Source for High Gradient Accelerator Research

A critical issue for multi-TEV linear colliders is the inability to demonstrate acceptable microwave performance with accelerating gradients greater than 80 MV/m at radio frequency (RF) pulse widths of 100 to 200 nanoseconds. This project will design, fabricate and test a high efficiency, deflection modulation power amplifier (Choppertron), and construct a unique test facility that will permit high power tests to be performed on high gradient accelerator structures. Phase I investigated a novel means of combining a charge enhancement technique with a spatially modulated, high-power (500-550 kV) electron beam; performed detailed microwave and beam optics analyses; and established design parameters for a high efficiency 20 MW 17 GHz Choppertron. In Phase II, final engineering design and manufacturing documents will be developed for the 20 MW Choppertron beam centerline components, the solenoid assembly, the evacuated rectangular waveguide transmission and diagnostic components, and the components required for interfacing the existing subsystems with the upgraded test facility. After fabrication and installation of the equipment, the focused and deflected beam characteristics will be measured, and the high power performance of the 17 GHz Choppertron will be evaluated. Commercial Applications and Other Benefits as described by the awardee: A new, high efficiency, short wavelength microwave source should find use in high gradient accelerator research and for high-peak-power commercial applications.