Autoresonance laser accelerator

Abstract

A laser-electron-acceleration scheme based on self-sustained cyclotron resonance is discussed. Nonlinear electron dynamics in combined axisymmetric magnetic and transverse laser radiation fields is investigated. Analytic solutions are given for a circularly polarized luminous (\ensuremath{\omega}/ck=1) radiation case, which allows time unlimited phase locking between the electrons and the accelerating electromagnetic wave. An appropriate tapering of the magnetic field in the superluminous case (\ensuremath{\omega}/ck>1) can also lead to significant accelerations, restricted by the maximum available strength of the guide magnetic field. We discuss the entrance conditions for the accelerated beam as well as its launching into the desirable autoresonance regime through a transition region. It is shown that the radiation losses in a 1-TeV accelerator are negligible. Also, high-current-beam acceleration seems to be feasible. Nd-glass lasers with intensity of ${10}^{18}$ W/${\mathrm{cm}}^{2}$ are capable of accelerating high-current electron beams from 0.25 to 2.5 GeV over 1 m by using a 100-kG guide magnetic field.