Arcing from coated surfaces: Test facility development and coating deposition using ion plating techniques

Electrical arcing from surfaces is recognized as a potentially deleterious source of plasma impurities for next generation fusion devices. Surface coatings and/or surface conditioning techniques can be applied to reduce the amount of such arc generated impurity atoms. In order to investigate the arcing phenomenon and to assess the arcing performance of various coatings and coating techniques, a unique experimental facility is being developed. This dual purpose facility, developed around an existing ion plating system, allows for the convenient joint studies of arcing phenomenon and coating deposition processes. Completed work includes the construction of an arcing test fixture for study of coating performance in a ''glow discharge to biased surface'' configuration, and the deposition of selected coating materials using ion plating techniques. Work is continuing toward the development of arc testing and diagnostic instrumentation