Net absorption of a laser light by relativistic electrons through net inverse bremsstrahlung in a longitudinal electrostatic wave was previously found to give rise to a very large net dc force. The predicted incident energy dependence of electron acceleration by co-propagating laser waves and the weaker longitudinal electrostatic waves is in qualitative agreement with the preliminary results of a recent Canadian laser-plasma electron acceleration experiment in which phase matching was not attempted. Furthermore, an analysis of the preliminary data indicates the existence of a non-Lorentzian force, which is the only force responsible for the net electron acceleration.
K Wendell Chen,
"Laser Electron Acceleration By Net Inverse Bremsstrahlung", Proc. SPIE 0664, High Intensity Laser Processes, (21 October 1986); doi: 10.1117/12.938687; https://doi.org/10.1117/12.938687