Controlled self-modulation of high energy beams in a plasma

A high energy particle beam propagating in a uniform plasma is subject to the transverse two-stream instability that first transforms the beam into the train of microbunches and then quickly destroys that train by transverse wakefields. By the proper longitudinal inhomogeneity of the plasma density, it is possible to stop the instability action at the stage of microbunches and form the bunch train that can resonantly excite plasma wakefields over a long distance. The latter feature is vital for proton beam driven plasma wakefield acceleration that was recently proposed as a way to bring electrons to TeV energy range in a single plasma section. (C) 2011 American Institute of Physics. [doi:10.1063/1.3558697]