Generation and transport of ultrashort phase-locked electron bunches to a plasma beatwave accelerator

The last five years have seen successful experimental efforts on ultrahigh gradient acceleration of electrons from laser- and electron-driven electron plasma waves. The challenges for future near-term experiments have now changed from proof-of-principle of high gradients to the production of a substantially high quality electron beam from a plasma accelerator. This paper discusses two aspects of this challenge, namely techniques for the synchronization or phase-locking of prebunched electron micropulses to the plasma accelerating structure, and the production and transport of the ultrashort microbunches themselves. Several phase-locking schemes unique to the plasma beatwave accelerator concept will be discussed as well as a more general discussion of microbunch production from RF photoinjector guns and the subsequent transport including space charge effects and electron transport optics.