Experimental and analytical studies of louvered first-wall systems for NIF

The first wall of the National Ignition Facility (NIF) target chamber will be a source of contamination for the final optics assemblies (FOA) debris s hields. The expected x-ray fluence on NIF can be as high as 2 J/cm(2) for 2 0 MJ target yields. This is sufficiently intense to mobilize first wall mat erial and contaminants that have been deposited on the first wall. Since 90 % of the aluminum target chamber surface area will consist of first wall pa nels, it is critical to choose a material that is not easily mobilized by t arget x-ray emissions. Additionally, it would be advantageous to have a fir st wall design that provides a sink for mobilized material in the target ch amber. With these issues at hand, a louver design has been proposed as the configuration of the NIF first wall. Experiments simulating the proposed lo uver geometry were fielded on Nova at x-ray fluence levels comparable to th ose expected on NIF. The results of these experiments were applied to the u nderstanding of NIF contamination issues and used as a benchmark for the TS UNAMI code. Numerical studies were performed to measure the collection effi ciency of the louver design where several parameters including louver lengt h, distance between louvers, and x-ray fluence were varied.