Results 311 to 320 of about 292,669 (354)
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A helium gas probe for use in cryosurgery
Cryobiology, 1984The design and testing of a prototype cryosurgical probe utilizing helium gas precooled with liquid nitrogen are described. An 8-mm-diameter probe produced an ice ball with a diameter of 28 mm after 10 min freezing using a helium gas flow rate of 42 liter/min. This indicated a surface heat transfer coefficient of 0.34 W/cm2 degrees K and temperature of
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Measurements on the velocity of sound in helium gas at liquid helium temperatures
Physica, 1954Synopsis From measurements on the velocity of sound in helium gas as a function of pressure at fixed temperatures between 4.22 °K and 3.60 °K we calculated the ratio of the specific heats and the specific heats self. Nearly straight lines are obtained for Cp/Cv as a function of pressure. The values are between 2.00 and 1.67.
G. Forrez, A. Van Itterbeek
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Determination of Impurities in Helium by Gas Chromatography
Analytical Chemistry, 1960In the method described a liquid nitrogen-cooled charcoal trap is used to concentrate the impurities, and a Type 5A molecular sieve column is used for separating hydrogen, oxygen, nitrogen, methane, and carbon monoxide. Carbon dioxide is determined in a separate sample using silica gel. (D.E.B.)
Authur Mosen, George. Buzzelli
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1970
Only small users of liquid helium — or those blessed with more money than they know what to do with — can afford to let helium out into the atmosphere. Where liquid helium is bought out, it is a matter of returning the helium gas in cylinders to the supplier.
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Only small users of liquid helium — or those blessed with more money than they know what to do with — can afford to let helium out into the atmosphere. Where liquid helium is bought out, it is a matter of returning the helium gas in cylinders to the supplier.
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The optimal helium fraction for air–helium gas mixture HDDs [PDF]
Microsystem Technologies, 2015 Helium-filled drives have recently been commercialized to enable a high recording density. However, because the use of helium increases production costs, binary gas mixtures such as air---helium have been investigated. In this paper, the dominant performance metrics of hard disk drives (HDDs) are the windage losses, the flow induced vibration (FIV ...
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Speech alarm and cycle helium gas monitoring of helium refrigerator
Indian Journal of Cryogenics, 2014Two helium liquefiers are running round-the-clock in parallel. One of them is always connected to the Superconducting Cyclotron in refrigeration mode. EPICS based alarm system is running with alert sound in computer speaker. But the fault cannot be located without opening the fault screen.
Abani Mukherjee +5 more
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Diffusion in helium-noble gas mixtures
Physica A: Statistical Mechanics and its Applications, 1982Abstract Diffusion coefficients have been measured of almost Lorentzian binary mixtures of He and the noble gases Ne, Ar, Kr and Xe. Measurements have been performed in the temperature range from 237 K to 420 K. The agreement with other experimental data is very satisfactory.
A.S.M. Wahby, M. Abdel-Rahman, J. Los
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Formation of positronium in helium gas
1973The formation of positronium in helium gas under an applied electric field has been investigated in order to derive a value for the momentum-transfer cross section, (σ m, of positrons on helium atoms. The major increase in positronium formation was noticed at Ɛ/D's of 60 V cmˉ¹ amagatsˉ¹ . Ɛ/D values up to 100 V cm-¹ amagatsˉ¹ were obtained.
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Gas Hydrate Formation for Mixtures of Methane + Helium and Ethane + Helium
Journal of Chemical & Engineering Data, 2003Equilibrium conditions of gas hydrates formed from methane + helium and ethane + helium mixtures are experimentally determined. As the helium concentration in gas mixtures increases, the equilibrium conditions shift to lower temperatures and higher pressures.
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Optical spectra of atoms in liquid helium and cold helium gas
The 14th international conference on spectral line shapes, 1999Lineshapes associated with the absorption and emission spectra of neutral atoms in liquid helium and cold helium gas are discussed. A neutral atom in liquid helium forms a microcavity due to a strong short-range repulsive force between the helium and impurity atoms, producing very broad and largely blueshifted absorption bands and relatively narrow ...
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