Complete Multipactor Suppression in Dielectric Loaded Accelerators Using a Solenoid Field

Multipactor discharges in dielectric accelerating structures are a major limitation on the performance of this otherwise very promising technology for future high energy physics machines and other applications. We will experimentally study a new approach, using an external solenoid field to completely suppress multipactor. This approach has been theoretically studied and verified in a 3-D numerical simulation. Under Phase I of the project, we completed the EM modeling, engineering design, and the fabrication of DLA structures based on two different materials. The final structures were assembled and bench tested. One structure has been installed with a solenoid at the NRL X-band magnicon. The first high power rf experiments on multipactor suppression will be completed in early 2013. The work in Phase II of this project will be aimed at a series of high power tests of the DLA structures constructed under Phase I at the NRL 11.4 GHz magnicon facility. We plan to systematically perform power loss and multipactor light emission measurements for different materials as a function of the applied solenoid field. Analysis of the results will be directly compared against the theoretical model and numerical simulations. We will build a compact low energy dielectric accelerator prototype for industrial or medical applications. We will investigate the option of using a permanent magnet solenoid. Finally, an experiment to accelerate electrons in the prototype dielectric structure will be performed. Commercial Applications and Other Benefits: Eliminating multipactor effects in dielectric accelerators will allow higher power and higher efficiency operation of these machines. This will represent a great leap forward for the use of dielectric materials in particle accelerators and high power rf generation applications.