DC gas discharge lamp having a thorium-free cathode

A DC gas discharge lamp, comprising:

• an anode;
• and
• a cathode comprising a first cathode segment, which forms the surface of the cathode at least in a region of the cathode which faces the anode and has an arc attachment region, within which an arc burning between the cathode and the anode attaches during lamp operation as intended;
• wherein the first cathode segment consists of tungsten with at least one emitter material for reducing the work function of electrons from the cathode;
• wherein the cathode is embodied in a manner free of thorium;
• wherein the at least one emitter material has a melting point of less than 3200 K;
• and
• wherein at least one part of the surface of the cathode outside the arc attachment region is formed by a diffusion barrier for the at least one emitter material;
• wherein the diffusion barrier is comprised of a coating applied on the surface of the cathode, wherein the coating comprises at least a first coating arranged in direct proximity to the arc attachment region, and a second coating arranged on the cathode surface at a greater distance from the arc attachment region than the first coating.