In this paper, atmospheric plasma spraying is used to produce metal-insulator-metal structures that emit ultraviolet light via electrical discharge when sufficient voltage is applied. The metal layers are sprayed with molybdenum alloy powders and the insulator, a 50 to 100 μm dielectric layer, is sprayed with zirconia powder. The authors describe the fabrication process, assess the characteristics of the layers, and present test results that quantify the radiant power of the emitted UV light. Output power and efficiency of the plasma-sprayed structures are compared with that of commercial excimer lamps and the effects of coating erosion due to electrical discharge are discussed. Paper includes a German-language abstract.

Conventional DC plasma torch designs lead to a circular cross-section of the emanating plasma jet. Consequently in surface treatment applications the plasma jet hits the substrate within a limited circular working area. Large scale workpieces therefore have to be scanned resulting in a time-consuming procedure. The innovative DC plasma torch system LARGE is characterized by the arrangement of the anode and the cathode opposite to each other on a common axis with a variable distance. The central body of the torch between the electrodes is divided into electrically insulated cascade plates. The plasma gas is injected perpendicular to the torch axis. Passing through the arc, the gas is transferred to the plasma state and leaves the torch laterally through a slit as a plasma jet with extended stripe width. The plasma torch LARGE is investigated by electrical, optical and enthalpy probe diagnostics. Shrouding the electrodes with an inert gas and feeding reactive gas mixtures as main plasma gas allow the torch to be used for plasma chemical reactions, too. Preliminary applications focus on preheating, surface modification of paper and plastic materials as well as on sterilization of nutrition packaging. The capability of plasma enhanced CVD is examined experimentally.