Coherent terahertz radiation from interaction of electron beam with rippled density plasma

摘要

An alternative free electron laser concept for producing coherent terahertz radiation is investigated. A weakly relativistic electron beam impinged on a rippled underdense plasma, at an angle to the ripple wave vector, interacts with a seed terahertz signal to produce a space charge beam mode. The oscillatory electron velocity due to the beam mode beats with the density ripple to generate a coherent electromagnetic wave in the terahertz frequency range in forward direction. For an electron beam with 5 MW power, one can obtain ～40 kW power at 1 THz frequency.