Staging for Wakefield Acceleration Experiment Hardware Development: Fast Kicker and High Power RF Delay Section

Linear colliders based on two-beam wakefield acceleration have an intrinsically modular design. A fundamental requirement of two-beam wakefield acceleration that has yet to be demonstrated is the staging of sequential accelerating modules. For a successful staging demonstration two key things have to be addressed: drive beam separation and the timing between the accelerated beam and wakes from different stages. Previous methods addressed the timing issue by sending the drive beam through a 180 degree bend, but this leads to problems with coherent synchrotron radiation and subsequent degradation of beam quality. We propose to use a fast stripline kicker for drive bunch train management. We estimate that the power requirement and turn-on time are well within a grasp of current technology. Synchronization of the main (witness) beam with wakefields generated by the drive beam can be done by a series of variable microwave power delay lines, which eliminates the need to bend the drive beam. We propose to use an overmoded TE01 mode based cylindrical waveguide as a delay line because of the reduced power loss of this mode. In the Phase I project, we have designed and built all necessary hardware to setup and demonstrate a major component of the staging process. Starting with initial staging experiment early in the Phase II work, we will demonstrate the entire staging process by the end of the project. Commercial Applications and Other Benefits: Staging is a key experiment that has to be demonstrated for the validation of the wakefield collider concept. If the main (witness) beam can be made synchronous with the drive beam wakefield generated in separate stages, and preservation of the main beam emittance can be shown, then a collider at a given energy can be designed by just stacking together the required number of wakefield modules.