Switched matrix accelerator

We describe a new concept for a microwave circuit functioning as a charged- particle accelerator at mm wavelengths, permitting an accelerating gradient higher than conventional passive circuits can withstand consistent with cy clic fatigue. The device provides acceleration for multiple bunches in para llel channels, and permits a short exposure time for the conducting surface of the accelerating cavities. Our analysis includes scalings based on a sm ooth transmission line model and a complementary treatment with a coupled-c avity simulation. We also provide an electromagnetic design for the acceler ating structure, arriving at rough dimensions for a seven-cell accelerator matched to standard waveguide and suitable for bench tests at low power in air at 91.392 GHz. A critical element in the concept is a fast mm-wave swit ch suitable for operation at high power, and we present the considerations for implementation in an H-plane tee. We discuss the use of diamond as the photoconductor switch medium. (C) 2001 American Institute of Physics.