Erosion-resistive coatings are provided on critical plasma-facing surfaces of an electrical gas plasma head for an EUV source. The erosion-resistive coatings comprise diamond and diamond-like materials deposited onto the critical plasma-facing surfaces. A pure diamond coating is deposited onto the plasma exposed insulator surfaces using, for example, a chemical vapor deposition processes. The diamond coating is made conductive by selective doping with p-type material, such as, but not limited to, boron and graphite.