A.M.Zabelin.

The invention solves a problem of beam quality improvement for the power gas laser with cross pumping, which gas-discharge cabinet consists of two electrodes. One of this electrodes is round or oval, and other- flat. For this purpose the resonator in such laser is executed as stable-unstable with one-sided output of beam, a plane of unstability is unrolled across a stream, and the resonator axis is disposed at a level of round or oval electrode in such a manner, that the resonator caustic transits between flat and oval electrode.