Plasma-wave generation and acceleration of electrons by a nondiverging beating optical beam

Plasma waves can be used to create efficient and small-sized electron accelerators. Despite the already demonstrated success in reaching GeV-scale energy gain in the motion of electrons, laser-induced wakefields still suffer from the transverse spreading and the loss of synchronization with the accelerating particles. In this work, to tackle these problems, we propose using a two-wavelength structured laser beam with a designed angular dispersion and adjustable group velocity in free space to efficiently excite a nondiverging plasma wave. This approach allows one to generate an electron bunch with low transverse spread and reach high average acceleration gradients.