A Choppertron RF Source for High Gradient Accelerator Research

The DOE-sponsored U.S. High Gradient Collaboration has determined that U.S. efforts should attempt to achieve the highest practical accelerator gradient in a working frequency range of 11.4 to 30 GHz. Although recent CERN studies suggest that 20 GHz is a near optimum value, facilities for conducting high gradient accelerator research are available only at 11.4 GHz in the U.S. (SLAC) and at 30 GHz in Switzerland (CERN). This project will develop a deflection modulation, phase stable power amplifier (Choppertron) to enable the research and testing of high gradient accelerators in the frequency range of 17 to 23 GHz. In Phase I, two 30pps, 800 nanosecond Choppertrons will be designed: (1) a 50 MW Choppertron based on the possible future availability of a 220 MW high-voltage electron-beam source, and (2) a 15 MW Choppertron, based on the presently-available, 50 MW, electron-beam test stand. By using existing diagnostic and RF drive equipment, costs will reduced, and operating frequency choices of 17.136, 19.0 and 22.848 GHz will be provided. During Phase II, the amplifier system will be fabricated and tested at high power, in order to evaluate high-phase stability and a klystron-like saturated drive characteristic. Commercial Applications And Other Benefits as described by the Applicant: The Choppertron should be readily reconfigured to provide phase-stable output power at integer values of the drive frequency (e.g., 11.424, 17.136 and 22.848 GHz) when using a 5.712 GHz drive. Commercial applications that require a range of frequency choices would benefit from this technology.