Description: The Princeton Poloidal Divertor Experiment (PDX) plans to use titanium gettering of hydrogen to provide the high pumping speeds required to capture the pulsed gas load which occurs in the region where the diverted plasma is neutralized. Detailed information with respect to hydrogen titanium film interactions under similar conditions was sought so that engineering decisions could be made with greater confidence. Pumping speeds for hydrogen on titanium films were determined by admitting a pulse of gas into the volume enclosed by the substrate and measuring the time constant of the pressure decay. The measurement was made periodically as the film was deposited, and when the maximum sticking coefficient was reached, sublimation was stopped and additional gas pulses admitted to determine the speed vs. hydrogen concentration in the Ti film. The amount of gas per pulse varied from 0.25 to 5 monolayers. Atomic hydrogen produced by thermal dissociation in a continuous measurement gave minimum-values for the sticking coefficient of 0.3 for a room temperature film. A summary of results is shown. Titanium film peeling tests were performed and sublimation sources were test operated. (auth)
Date: January 1, 1976
Creator: Martin, G.D.
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