The effects of radiation losses and atomic motion in a distributed feedback induced by Bragg reflections in an electron-beam-channeling x-ray laser are investigated. Standing-wave fields with nodes in the atomic sites are generated in this cavity-mirror structure in single crystals, thereby reducing the losses located close to the atomic sites. An explicit expression for the low-threshold gain is derived which depends on the absorption, temperature, and on the order of Bragg reflection. It is noted that diffraction from several sets of atomic planes which satisfy the Bragg condition simultaneously may further reduce the threshold gain. These distributed-feedback schemes have possible application in reducing beam high-current requirements by many orders of magnitude.

• Received 19 December 1988

DOI:https://doi.org/10.1103/PhysRevA.39.5791