Efficient laser–electron interaction via perfect vortex beam

Laser manipulation methods of the electron beam can significantly improve the coherence and peak power of accelerator-based radiation sources, especially seeded free electron laser and storage ring. However, the limited average power of the modulation laser poses a bottleneck for increasing the repetition rate of these coherent radiation sources. To address this challenge, improving the efficiency of laser–electron interaction is essential. In this Letter, we propose an efficient scheme to enhance the laser–electron energy coupling by employing a perfect vortex laser beam within a helical undulator. The electron beam trajectory is highly consistent with the helical wavefront of the laser field, which improves the utilization efficiency of the optical electric field. Three-dimensional time-dependent simulation results indicate that the repetition rate can be improved by over two orders of magnitude over the conventional Gaussian laser beam at the same input power. We anticipate that the proposed scheme will pave the way for the development of high repetition rate coherent radiation sources.