Cryocondensation pumping of thick films of hydrogen and deuterium

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In order to obtain engineering data for design of large capacity cryopumps for hydrogen, deuterium and tritium, an apparatus was built where pumping speeds and sticking coefficients can be studied as a function of surface coverage for different leak rates. In addition, thermal conductivity and thermal absorption of these frozen gases can be inferred from the measurements of pumping speed equilibrium pressure and the helium boil-off rate. The following changes in the above parameters were observed when the surface coverage was increased from a few atomic layers to 3.8 x 10$sup 20$ molecules cm$sup -2$ for H$sub 2$ and 1.2 ... continued below

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10 p.

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Halams, H.J. & Bamberger, J.A. January 1, 1975.

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Description

In order to obtain engineering data for design of large capacity cryopumps for hydrogen, deuterium and tritium, an apparatus was built where pumping speeds and sticking coefficients can be studied as a function of surface coverage for different leak rates. In addition, thermal conductivity and thermal absorption of these frozen gases can be inferred from the measurements of pumping speed equilibrium pressure and the helium boil-off rate. The following changes in the above parameters were observed when the surface coverage was increased from a few atomic layers to 3.8 x 10$sup 20$ molecules cm$sup -2$ for H$sub 2$ and 1.2 x 10$sup 21$ molecules cm$sup -2$ for D$sub 2$: the pumping speed decreased about 10 percent while the equilibrium pressure and helium boil-off were unchanged within the limits of our measuring accuracy; changing the gas leak rate from 0 to 2 x 10$sup -3$ Torr liters sec$sup -1$ cm$sup -2$ also decreases the pumping speed by approximately 10 percent. From the above measurements it is inferred that thermal absorption to frozen H$sub 2$ and D$sub 2$ is negligible. Based on the information obtained in our investigation we designed a cryopump having a pumping speed of 10$sup 5$ liters sec$sup -1$ for hydrogen. (auth)

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10 p.

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Dep. NTIS

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  • IEEE 6. symposium on engineering problems of fusion research, San Diego, California, USA, 17 Nov 1975

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  • Report No.: BNL--20681
  • Report No.: CONF-751125--81
  • Grant Number: None
  • Office of Scientific & Technical Information Report Number: 4131913
  • Archival Resource Key: ark:/67531/metadc867501

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • January 1, 1975

Added to The UNT Digital Library

  • Sept. 16, 2016, 12:32 a.m.

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  • April 17, 2017, 2:44 p.m.

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Halams, H.J. & Bamberger, J.A. Cryocondensation pumping of thick films of hydrogen and deuterium, article, January 1, 1975; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc867501/: accessed October 16, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.