On the prospects of using runaway electron beams generated in an open discharge for the pumping of metal-vapor lasers

The excitation of gas lasers with the help of electron beams (e-beams) is, at the present time, one of the most promising methods of pumping. In most of the conventional methods, an electron beam is produced as a result of a collisionless acceleration of electrons due to the low gas density in a diode of an accelerator. Because of this, an accelerative gap should be hermetically isolated from a laser cell, which makes the technique of e-beam injection into the active region quite complicated. A radical solution to the problem would be the production of an e-beam in the gas whose density in the accelerative gap corresponds to the working pressure of the laser. This would allow one to place an accelerator in one chamber with the laser. The generation of a beam in a high-density gas would become possible when one provides the conditions for an effective transition of electrons into the runaway regime. Such a motion of electrons can be achieved in a strong electric field as a result of the decreasing cross section of the electron-atom interaction as sufficiently high energy. The runaway effect is manifested in the case where the electrons moving under the action of a strong external field obtain kinetic energy comparable with the potential difference. The kinetic energy is many times greater than that spent in one collision. Despite the considerable number of collisions, the electrons are transmitted into the steady acceleration regime, and their motion becomes almost directed, thus forming a beam. The present paper is devoted to the development of a physical-mathematical model of an open discharge, the calculation of its characteristics, and the estimation of the potentialities of e-beam pumping of metal-vapor lasers.