An efficient microwave power source: The free-electron laser afterburner

Abstract

A kind of microwave power source, called a free-electron laser (FEL) afterburner, that consists of a free-electron laser buncher and a slow-wave output structure sharing a magnetic wiggler field with the buncher is proposed. The buncher and the slow-wave structure can operate in either a traveling-wave state or a standing-wave state. In the buncher, the wiggler field together with the radiation field makes an electron beam bunched, and in the slow-wave structure the wiggler field keeps the beam bunched while the bunched beam interacts strongly with the slow-wave structure and thus produces rf power. The bunching process comes from the free-electron laser mechanism, and the generating process of rf power is in a slow-wave structure. A three-dimensional, time-dependent code is used to simulate a particular standing-wave FEL afterburner and it is shown that rf power of up to 1.4 GW at 17.12 GHz, can be obtained from a 1 kA, 5 MeV electron beam with an energy spread of less than 1% and an emittance of less than 0.5×10−3 π rad m.