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Abstract:
Extensions to conical orifices of Clausing's analysis of angular distribution of molecules effusing from cylindrical orifices resulted in numerical values for transmission probabilities and recoil-force correction factors which are tabulated. With these results, it is demonstrated that the optimum orifice geometry for (1) recoil force measurements is a diverging conical orifice with semi-apex angle of 30 degrees, (2) delivery of maximum fraction of effusing molecules onto (or into) a target (aperture) is a long cylindrical orifice. Modifications to the angular distribution apparatus are described and experimental results given for four orifices and two gases over the pressure range 5 to 900 dyn/sq. cm. Additional results for experimental transmission probabilities of orifices determined by the Multicell technique are generally in agreement with theoretical values within 2 to 5%. The Miker technique for simultaneous determination of vapor pressure by rate of effusion and by recoil force measurements was refined to the point that recoil force data are as reproducible as rate of effusion measurements. A new furnace and a modified automatic control system for the microbalance are described.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Description: |
Final rept. 1 Sep 1964-31 May 1967 |
| Pages: |
94 |
| Report Date: |
NOV 1967 |
| Contract Number: |
657, AF336578767 |
| Report Number: |
0960466 |
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