Abstract: An improved electrode design for reducing discharge instability, especially in white light lasers. The apparatus consists of at least one cathode electrode (12) arranged between anode electrodes (14), said cathode being divided into two equally long tube parts (15) designed with inner cylindrical electrode surfaces (A.sub.1, A.sub.2) between which a widened portion (16) is located and each anode electrode is connected via and insulator (13) to the end of each tube part (15) facing away from the widened portion. This widened portion of the cathode serves to divide the cathode which in turn stablized the current and the current density. It can also serve as a metal reservoir.