Joining Alumina to Sapphire for Copper Vapor Laser Tubes

The technology for building copper vapor lasers has existed for years. The joining technology for producing sealed copper vapor lasers did not. Thus, our focus during Phase I research was to explore means of joining alumina to alumina and alumina to sapphire for high temperature applications. We felt that it was imperative to explore more than one joining technique, and for a given technique, to investigate a range of conditions of compositions, or both. The motivation for this approach was twofold. First, it was beyond the scope of Phase I research to exhaustively explore the mechanical and chemical stability of all joints produced by a broad assortment of joining techniques, particularly for the timeframes of interest for a sealed copper vapor laser. We recognized that joining methods that produced bonds of adequate quality to survive limited thermal cycling and limited exposure to copper might prove to be inadequate for long-term use. Thus, if the method that appeared most satisfactory in Phase I testing proved inadequate for fabrication of sealed copper vapor lasers, we would have the needed experience with alternative joining approaches to adjust and adapt rapidly. Second, we felt that it was possible that more than one joining method in producing the total system. Those who had chosen to explore only one joining method would lack this flexibility.