Optimal wakefield excitation and particle acceleration in a relativistic counterstreaming electron beam

The wake excitation of nonlinear plasma waves in a relativistic counterstreaming electron beam and the consequences for charged particle acceleration are discussed. The basic idea is to use an optimally shaped high-energy electron bunch as a driving source to generate a large-amplitude, high-phase-velocity nonlinear plasma wave in a high-density relativistic counterstreaming electron beam. A trailing charged particle bunch can then be loaded onto the wave and accelerated to a high energy. Discussions of staged acceleration are also included. It is found that the relativistic effects resulting from the relativistic streaming of the counterstreaming electron beam can provide Lorentz effects to reduce the two-stream instability for obtaining a higher transformer ratio, to achieve a longer plasma wavelength for easier beam loading, and to ease the technical difficulty connected with generating a well-shaped driving electron bunch