STUDY OF DEGRADATION MECHANISMS IN HIGH-TEMPERATURE FRIT-SEALED OPTICAL COMPONENTS FOR PB-VAPOR RAMA CELLS

IT IS PROPOSED TO DESIGN, BUILD AND TEST AN EXPERIMENT TO DETECT AND MEASURE THE MIGRATION OF FRIT SEALING MATERIALS TO THE WINDOWS OF HOT-WINDOW PB-VAPOR RAMAN CELLS. THE PROPOSED EXPERIMENT CONSISTS OF A FRIT-SEALED WINDOW ON A SMALL TEST CELL (SUPPLIED BY NORTHROP ELECTRONICS DIVISION) PLACED IN THE HOT ZONE OF A SMALL FURNACE AT TEMPERATURES UP TO 1500 DEG C. THE FRIT MIGRATION WILL BE MONITORED BY OBSERVING DECREASED TRANSMISSION OF A HENE LASER THROUGH THE TEST PIECE. FOLLOWING DEMONSTRATION OF FEASIBILITY OF THIS EXPERIMENT, A TEST PLAN FOR RAMAN CELLS WILL BE PREPARED FOR MORE DETAILED STUDIES IN PHASE II. IN ADDITION TO FRIT MIGRATION, PHASE II WILL STUDY OTHER LONG-TERM LIFE LIMITING ISSUES SUCH AS HIGH TEMPERATURE DAMAGE THRESHOLD, FORMATION OF STRIATIONS ON WINDOWS, ETC.