Long-Pulse, High-Power Free-Electron Laser with No External Beam Focusing

Abstract

We report the results of a free-electron laser experiment which has produced 1-2-\ensuremath{\mu}sec duration pulses of \ensuremath{\sim} 30-GHz radiation at power levels up to 4 MW. This is the first free-electron laser in the high-current operating regime to employ no external electron-focusing field. Consequently, there is no cyclotron emission, and the output radiation is unambiguously identified as free-electron laser emission.