Mechanisms of Stabilization and Terahertz Radiation from Short Electron Bunches in Two-Wave Regimes

Powerful coherent terahertz radiation from short electron bunches formed in laser-driven accelerators is in great demand for many applications including pump-probe experiments at XFELs. If the electron bunch is shorter than emitted wavelengths a coherent radiation process does not need a special electron bunching and starts in radiation section immediately. However, at relatively low electron energy and high particle density, a strong mutual Coulomb repulsion of particles rapidly expands dense bunches and drastically decreases radiation efficiency. Stabilization of the bunch length or even bunch compression may be provided by various methods that were suggested in previous works. Ones of simplest and efficient seem the proposed below methods based on the use of two-wave regimes of radiation.