ARC COATING APPARATUS HAVING ARC IGNITION DEVICE

摘要

There is disclosed for a vacuum arc plasma generating system an ignition device that includes an elongated metallic member of length L with an inner edge juxtaposed a distance D from the edge of the target surface of the cathode. An insulating member with a bridging surface is formed preferably of a material such as boron nitride and is interposed such that the bridging surface connects between the ignitor member and the edge of the target surface. The ignitor member and insulating member may be ring-shaped to surround a circular target surface. The inner edge of the ignitor member preferably is formed of a multiplicity of teeth in contact with the bridging surface. An electrically conducting film is deposited on the bridging surface. A simple electrical connection is disposed between the ignitor member and the anode of the plasma system, making the ignitor member a supplemental anode. In onepreferred embodiment the length L is sufficiently large and the distance D is sufficiently small for the conducting film to evaporate upon imposition of the d.c. arc voltage between the cathode and anode, thereby initiating the arc without the need for an additional starter voltage power supply.