Vergleichende Untersuchungen an gepulsten Laser- und Vakuumbogenplasmen

The high vacuum arc process is a practicable way to produce thin and hard carbon coatings for wear protection in a industrial relevant time. In spite of the high application-caused interest the fundamental processes of cathode erosion and plasma formation are still on discussion. Comparable investigations on laser and arc plasmas allow a better understanding of these processes. Laser radiation and arc current are able to produce local power densities higher than 108 Wcm-2. Near this points the target material is evaporated and converted in a plasma state. The plasma parameters of laser and vacuum arc plasmas are in the same range. These plasmas are characterized by high temperature and excitation as well as a high expansion energy of the plasma ions. In case of laser irradiation the process of plasma formation is a combination of material evaporation, plasma heating and plasma expansion. Within this contribution the basic ideas of plasma formation by laser irradiation are transferred t o the vacuum arc evaporation. It is shown, that this model processes is able to explain the processes of cathode erosion and plasma formation without contradiction in case of vacuum arc evaporation as well. The investigations are supported by SEM-pictures of arc erosion areas and the comparison with pictures after laser irradiation.