High Power RF Windows with Improved Multipactor Coating

High power RF windows are required for high power RF sources and accelerators systems. Many of these devices operate at UHF frequencies and below requiring large diameter RF windows capable of transmitting high peak power at high duty. The large size significantly complicates vacuum-tight fabrication and application of robust, uniform coatings to suppress multiplactor emission. New, innovative techniques and processes are required to build and coat these large windows. Calabazas Creek Research Inc. (CCR) is proposing to investigate window fabrication and assembly techniques to mitigate the risk associated with production. CCR will investigate innovative brazing fixtures and techniques allowing sealed windows without brazing. The program will also investigate Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD) as potential options to apply robust multipactor coatings. The challenge will be identifying materials compatible with these processes that are effective in reducing secondary electron yield without excessive RF loss. Thousands of high power RF windows are produced each year, primarily at higher frequencies more amenable to standard fabrication techniques and coating application methods. This program will enable window production at lower frequencies for a new class of RF sources and accelerator applications. It could also identify a more cost effective multipactor coating process for the broad range of RF windows built each year.