Miniaturization of diffraction-radiation generators

Experimental results are presented pertaining to the miniaturization of quasi-optical diffraction-radiation generators (i.e., free-electron lasers). Data are presented on generators with short-focus open resonators whose dimensions are commensurable with the length of the generated wave. It is shown that the characteristic dimensions of a quasi-optical open resonator can be reduced within the conservation limits of the resonator symmetry properties: two open resonators with the same generalized parameters have the same scale eigenfunctions, diffraction losses, and natural resonant frequencies.