New generation issues in the beam physics of rf laser-driven electron photoinjectors

摘要

Abstract: The beam dynamics of bright electron beams produced by Photo- Injectors brought up to evidence, during the last few years, a number of new aspects concerning the physics of intense relativistic charged particle beams which are far from thermal equilibrium. The theoretical understanding of these issues has become quite mature only recently, well after the first measurements on such beams were done at several laboratories which are active in the development of Photo-Injectors. This has been due mainly to the fact that the traditional formalism based on rms description of the beam distribution, via the envelope equation, fails to explain the coherent collective plasma motion which dominates the behavior of these beams: in this paper a complete description based on a generalized model will be presented, able to describe both the collective (laminar) regime, which dominates the first part of the injector, and the transition into the thermal regime, which dominates the dynamics into the following booster Linac. The impact of such a model on the performances in the generation of high brightness electron beams is finally discussed. !17