Laser-driven electron cyclotron autoresonance accelerator with production of an optically chopped electron beam

Analysis is presented of the gyroresonant acceleration of electrons in a va cuum using a focused laser. Continuous and equal acceleration is shown for electrons injected at all optical phases over an interaction length of tens of centimeters. Beam stalling is avoided as beam energy increases. Acceler ation from 50 to 178 MeV is predicted for a 4 TW, 10.6-mu m laser focused t o a waist radius of 1.0 mm; these parameters correspond to a planned experi ment. A beam stop with an off-axis hole after acceleration is shown to crea te a train of optically chopped bunches with 3-fs bunch lengths and a 35-fs period.