Volume free electron lasers

Volume free electron lasers (VFELs) are a new type of radiation sources using volume distributed feedback. The dispersion equation allowing to find the vacuum VFEL gain in the single-mode generation regime is considered. It is shown that a vacuum VFEL provides a more effective lasing process as compared with conventional FELs using one-dimensional distributed feedback (DFB). The VFEL provides the possibility to design compact sources in various spectral ranges. Therefore, it may be interesting for diverse applications in different wavelength ranges, from millimeter to X-ray. A VFEL can be realized on the basis of existing accelerators.