Brazed ceramic window for ion Bernstein wave heating

The paper explores an innovative design of a brazed ceramic window for use on the FT-U Tokamak at Laboratori Gas Ionizzati, Frascati, Italy for the Ion Bernstein Wave (IBW) Heating Experiment. The window was designed and fabricated by the Vacuum Braze Shop of the Princeton University Plasma Physics Laboratory. Ion Bernstein wave power of 600 kW at a frequency of 433 MHz will be transmitted for 0.5 seconds into the FT-U Tokamak. In-the past, IBW heating was accomplished by the use of an antenna inside the Tokamak. The window, which provides an ultra-high vacuum boundary for the Tokamak, allows a pair of waveguides carrying Ion Bernstein Waves to couple efficiently to the plasma. This type of configuration affords several advantages over placement of an antenna inside the Tokamak. By eliminating the invessel antenna, reliability is increased for the IBW Heating Experiment. In addition, maintenance is facilitated as all major components are more accessible to personnel. The window is comprised of two individual windows of high-purity alumina, brazed into a titanium alloy flange