Quasi-monoenergetic electron beam from LWFA: analytical approach

Analytical dependence of the energy spread of electron beam on time and injection duration has been obtained with the 1D model of the quasi-linear laser wakefield electron acceleration, presented as phase portraits of electron energy relative to the plasma wave phase. The method for producing electron beams with variable energy and a lower energy spread compared to a standard bubble-like approach by transferring to a deaccelerating part with another phase trajectory (by reducing the plasma amplitude of a wave) has been developed. The analytically obtained results successfully describe key features of the previously obtained in Tsymbalov et al (2024 arXiv:2403.19828) experimental and numerical (PIC) data.