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Optical constants of Na and Li in the form of evaporated thick solid films have been determined between 0.6 and 3.8 eV by ellipsometry. Measurements were made at room temperature through the quartz substrate at the quartz-metal interface. The optical conductivity of Na agrees well with the earlier data of Smith, while that of Li exhibits considerable differences from the results of Mathewson and Myers. The parameters of the nearly-free-electron model have been derived from the real part of the dielectric function, and the results compared with previous data.

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An experiment has been performed on the Impurity Study Experiment (ISX-B) tokamak to test beryllium as a limiter material. Beryllium is an attractive candidate for a limiter and has been proposed for use in the Joint European Torus (JET) experiment. A temperature-controlled, segmented, beryllium top-rail limiter was located inside the plasma radius described by the existing titanium limiters. An extended set of diagnostics was added for measurement of scrapeoff and limiter parameters. These included visible and infrared monitoring systems, probes, and surface analysis experiments. Tokamak experiments included parameter surveys of both Ohmically heated and neutral-beam-heated plasmas and an extended fluence test of the limiter. The most significant effect of operation with a beryllium limiter was the reduction in low-Z impurities caused by gettering action of beryllium deposited on the liner walls. The experiment required the design and implementation of contamination control apparatus and work procedures to prevent the accidental dispersion of beryllium dust.