Electron acceleration by the self-generated magnetic field of multiple laser pulses in plasma

The acceleration of electrons by the self-generated quasi-static magnetic field in the interaction of n laser pulses with a plasma is investigated. The relativistic dynamics of a single electron is followed numerically. It is found that the electron can be much more effectively accelerated by n laser pulses, each with amplitude a0 and having a fixed frequency difference from the preceding one, than by a single pulse with amplitude na0. The large enhancement of acceleration can be attributed to stochastic-like resonance between the electron motion at the beat-frequencies of lasers and at the cyclotron motion frequency.