Capture Coefficients of Gases at 77°K
The rate of impingement of molecules on a cryosurface for any gas in the free molecular region can be calculated from kinetic theory. However, the actual pumping speed must be measured experimentally since all the molecules that strike the cryosurface are not captured. This effect is described by the capture coefficient. The latter is defined as the ratio of the measured pumping speed to the theoretical rate of strike.
KeywordsMethane Crystallization Ethyl Acetone Hydroxyl
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