ADVANCED INSULATING COATINGS FOR PLASMA CONFINEMENT SYSTEMS

ELECTRICAL INSULATORS IN PLASMA CONFINEMENT SYSTEMS CAN BE EXPOSED TO AN EXTREMELY HOSTILE ENVIRONMENT, INCLUDING BOMBARDMENT BY ENERGETIC PARTICLES, ULTRAVIOLET AND X-RAY RADIATION, RAPID THERMAL CYCLING, AND HIGH RF AND DC VOLTAGES. THE INSULATORS MUST OPERATE RELIABLY IN THIS ENVIRONMENT AND, ADDITIONALLY, MUST NOT GENERATE SIGNIFICANTIMPURITIES THAT CAN DISTURB THE PLASMA RADIATION BALANCE ANDSTABILITY. THE PROPOSED PROGRAM WILL STUDY THE USE OF ION BEAM ENHANCED DEPOSITION (IBED) TO FORM INSULATING REFRACTORY COATINGS OF LOW AVERAGE ATOMIC NUMBER. THE IBED TECHNIQUE USES PHYSICAL VAPOR DEPOSITION WITH SIMULTANEOUS BOMBARDMENT BY ENERGETIC IONS TO YIELD COATINGS WITH SUPERIOR ADHESION, CRYSTALLINITY, MORPHOLOGY, AND HIGHLY CONTROLLED STOICHIOMETRY. THE PHASE I EFFORT WILL INCLUDE DEPOSITION AND TESTING OF HARD, ADHERENT COATINGS OF BORON NITRIDE, ALUMINUM NITRIDE, SILICON NITRIDE, AND ALUMINA. ENCOURAGING RESULTS WOULD LEAD TO PHASE II IN WHICH THESE AND OTHER COATING MATERIALS WOULD BE OPTIMIZED AND TESTED INA PLASMA ENVIRONMENT.