Some experimental results of a x-ray preionized homogeneous discharge laser at high gas pressures are presented. In this device a multi-arc-channel rail gap switch is used to create a fast voltage rise time

and a water-dielectric transmission line is employed as the discharge energy source. Homogeneous discharge lasts about 70 ns in a typical XeCl* gas mixture of 2-5 atm

and a laser output energy higher than 1.2 joules has been obtained in an active volume ot 2.0×1.5×70 cm3.