Confined Electron Laser

Free-electron laser (FEL) is currently the only viable solution for producing strong THz radiation pulses and coherent beams in a hard x-ray regime, one of the ground-breaking inventions in the twentieth century. Nevertheless, the large size and high operational costs of an FEL has limited its use in research experiments and for advancing the technologies in the THz and X-ray radiation spectrum. In this contribution, we introduce the confined electron laser (CEL) concept for producing radiation with similarities to FEL outputs, but with less limitations. By confining the electrons using the gradient forces inside an optical cavity, electron beams with high charge densities and low divergence can be realized. This CEL concept can result in orders of magnitude improvements in the source efficiency and coherence of the radiation for compact setups compared with the FEL concept.