be circulated via pipes 53 and 54 or replenished as required via such pipes there may be provided a plurality of heat pipes 55 for heat removal the magnet 50 can be a permanent magnet or a solenoid a dc voltage is applied to the anodes and cathodes establishing an electric field between these the magnetic field being orthogonal respective the electric field the resulting lorentz forces cause a circulation of the plasma through regions 51 and 52 whereby heat is circulated to and removed mainly via heat pipes 53 and 41 55 49 the intensity of the magnetic field is not critical in this special configuration and even a rather weak field results in a pronounced power output increase as shown in fig6 the resonator is folded by two flat mirrors 55 and 56 having a 100 reflectivity which are of rectangular shape and which are at an angle of 90 u00b0 with each other at axial ends of regions 51 and 52 at the opposite ends there are provided a metallic total reflectivity mirror 57 with cylindrical curvature and rectangular shape there is further provided an out put coupler mirror 58 with predetermined reflectivity so as to optimize the laser output of the gain region there can also be used an unstable folded cylindrical resonator configuration with a cylindrical output lens 58 as illustrated in fig6 in a similar manner in fig2 there are provided at the ends of the cathode 22 dielectric cylinders 35 and 36 respectively or corresponding enamel or similar coatings with a good seal to the cathode at the end of the region 23 between the anodes cathodes there are provided a.