Accelerated testing for extended service AMTEC cells

AMTEC cells are built with readily available materials, β´´-alumina, stainless steel, Mo, Ta, TiCuNi and TiNi brazes, and TiN electrodes. The long term cell performance is dependent on the stability and inertness of these materials in the high temperature Na environment. The task of selecting materials and verifying that they will perform for long times (15 years for a deep space probe) is addressed. Accelerated testing methods and models to utilize the accelerated test data are being developed. A six and twelve month accelerated test plan to evaluate the BASE/Braze/Electrode/Current Collector (BASE Assembly) interfaces in Na vapor at 1200, 1100, and 1000 K is described. An accelerated wick testing program is also discussed. The as-built BASE assembly braze interfaces have been evaluated. TiN electrodes, exposed for about 4000 hours at 1073 K are examined. This information illustrates the direction being taken for evaluating life test results and developing models for life predictions