Numerical simulations of intense charged-particle beam propagation in a dielectric wake-field accelerator

The propagation of an intense electron beam through a long dielectric tube is a critical issue for the successful demonstration of the dielectric wake-field acceleration scheme. Due to the head-tail beam breakup instability, a high-current beam cannot propagate long distances without external focusing. In this paper we examine the beam handling and control problem in the dielectric wake-field accelerator. We show that, by using an externally applied focusing and defocusing channel around the dielectric tube, a 150-MeV, 40-nC beam can be controlled and will propagate up to 5 m without significant particle losses for the proposed 15.6-GHz dielectric structures. We have also studied the case of a 100-nC beam propagating in a 20-GHz dielectric structure. Particle dynamics of the accelerated beam is also studied. Our results show that for typical dielectric wake-field accelerator structures, the head-tail instability of the accelerated beam can be conveniently controlled in the same way as the drive beam.