Fiber optic diagnostics for Z-experiments

Summary form only given, as follows. Quartz optical fibers provides an inexpensive, compact, radiation resistant, electrical noise immune shock diagnostic for our experiments on the Sandia National Laboratories Z-machine. Z fires a 20 megampere pulse of current into a cylindrical 20 mm diameter array of 12 micron tungsten wires. The resulting J/spl times/B implosion stagnation generates a blackbody temperature of about 140 eV. This radiation pulse is coupled into our experiment packages and shocks the containment wall of the package and the fibers positioned along the outside of the wall. A shock pulse entering the fiber heats the fiber to luminescent conditions producing an intense light pulse with sub-nanosecond rise time. The visible pulse is transmitted via fiber to an optical streak camera and/or to an Avalanche PhotoDiode (APD) optical-to-electrical converter then to fast digitizers for recording. The diagnostic fiber bundle consists of multiple single strand 100-micron fibers (Polymicro #FVP-100-110-125) that are positioned in precision machined fixtures to accurately locate the polished fiber ends in intimate contact with the outside gold wall of our experiment packages. The fibers are enclosed in a flexible steel radiation shield from the experiment to a specially designed vacuum bulkhead fitting. Once outside the Z-machine vacuum vessel the fibers are terminated in a standard type ST connector. We present the design of our inexpensive fiber optic shock sensor and results from some of our Z-machine experiments.