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Diffusion of gases across porous media
Classified
abstracts
1332-1345
16. GASES AND SOLIDS 16 1332. Ultrahigh vacuum techniques. (USA) This study was conducted on hydrogen permeation through tungsten and on the replacement of one adsorbed gas by a second from the gas phase. Significant results have been obtained on the H,-W system and some supporting work on the N,-W and H,-MO systems. R Frauenfelder et al, Rep WERE-2823-21, May 1966, (Westinghouse Corp, Pittsburgh,
Pa Research Labs). 16
The influence of oxygen in the ultrahigh vacuum range on electrical properties of CdS. (USA) Measurement of adsorption and desorption of oxygen in the range between 2.10-12 and 5.1O-8 torr and corresponding influences on photo-conductance on CdS single crystals are reported. Partial pressures were measured with a sensitive mass spectrometer located directly in front of the crystal. A typical desorption curve is given for amu 16. Effects of other gases predominant in the vacuum system such as hydrogen and carbon dioxide were also studied. K W Boer and R Schubert, Rep AROD-4461; TR-8; AD-637857, 1333.
July 1966 (Delaware
Univ, Newark,
values. These measurements were made under vacuum, initially reaching a pressure of about 5 x lO-B torr. In the mass-spectrometric measurements, three samples were placed in Knudsen crucibles and a pressure at least as low as 1O-’ torr was achieved. Two mass spectrometers were used-a high temperature, magnetic type and a time-offlight type. P G Wahleck and P W Gilles, J Chem Phys, 46 (7), 1st April 1967, 2465-2473. 17 :28 1339. Evaporator for investigation of the thermodynamic characteristics
of high-melting point materials. (USSR) Design of a Knudsen type evaporator for the MKh-1308 massspectrometer is described. The test material is placed in a tungsten crucible heated to 2700°C by an electron beam with power of up to 2kW. The working pressure is 3 x lo-’ torr. The effusion chamber can be simply adjusted during the operation. The device was proved by measu&g the sublimation temperature of La,O, in the temperature range 1490 to 2190°C. which was found to be 435&15 kcalinmol. S NBushkovich et al, iavodsk Lab, 33 (3), 1967, 376-377 (in R&an). 17 :33 1340. Liquid-helium-cooled platform
for an electron microscope.
(Japan)
Dept ofPhysic.& 16
1334. Diffusion of gases across porous media.
(USA) The basic laws of gaseous diffusion in porous media are derived from an extension of the “friction model”, without recourse to detailed kinetic theory. K S Spiegler, Ind Engng Chem, Fundamentals, 5 (4), Nov 1966, 529. 61 1335. Bonding energy of adsorbed Cs atoms with the tungsten crystal
(110) and (IOO)faces. (USSR) Isobars were measured for the adsorption of caesium on the (110) and (100) faces of tungsten single crystals and, from those values, relations between the adsorption temperature and Caesium surface concentrations were calculated. The adsorption temperature was established as 3.2 eV for the (110) face and 2.8 eV for the (100) face, for very small caesium concentrations, with a nearly linear fall of these values down to 0.8 eV at 5 x lo’* atoms per cm2 for both faces. V M Gavrilyuk et al, Fir Tverd Tela, 9 (4), Apr 1967, 1126-1128 (in Russian).
In the platform described the liquid helium flows through a thin copper pipe around the specimen holder, allowing specimen movement for observation. The holder and pipe are enclosed in a shield case kept nearly at liquid nitrogen temperature. The specimen can be exchanged by means of a conventional mechanism without breaking the vacuum. Observations of the magnetic effect in a superconducting film are described. H Watanabe and I Ishikawa, Japan J Appl Phys, 6 (I), Jan 1967,83-88. 18. GASEOUS ELECTRONICS 18 1341. Spectra of low frequency oscillations of vacuum arcs. (USSR) Arcs were produced from Mg, Zn, Cd or Bi at 10-j torr and oscillations of the arc potential were scanned at the frequency range of 20 kc/s to 30 MC/S. No noise was observed above 1 MC/S and in the steady state noise having a maximum below 200 Kc/s depends only weakly on the arc current. P E Belensov and A A Plyutto, Zh Tekh Fiz, 37 (2), Feb 1967, 3OG306 (in Russian).
17. THERMODYNAMICS
17 1336. Advanced studies on multi-layer insulation systems. (USA) Analytical and experimental studies are reported on the performance of multilayer insulation systems to reduce the heat leak rate into stored cryogenic propellants carried in space vehicles under varying environments. Experimental results showed that multilayer insulations with spacers of two or more materials are most efficient because each component can be selected to perform a specific function. Emittance stability of silver and copper coatings was highest under exposure to high humidity, carbon dioxide and salt environments. Commercial sources of good quality, low emittance shields consisted of polyester film, vacuum metallized on both sides with aluminium, silver and gold. Anon, Rep NASA-CR-54929, June 1966 (A D Little Inc, Cambridge, Massachusetts). 17 :42
temperature vaporization and thermodynamics of the titanium oxides. 1. Vaporization of the crystalline phases. (USA) The vaporization behaviour of the titanium-oxygen system has been established by experimental measurements of the change in composition of the solid residue accompanying vaporization as determined by x-ray diffraction, chemical analysis and color of sample. The solid phases studied were T&O, TiO, TieOs, T&O,, T&O,, TiBOB,TiloOlp and TiO%. Details of preparation of samples are given and all vaporizations were performed under high vacuum (usually about 1O-5 torr). P W Gilles et al, J Chem Phys, 46 (7), 1st April 1967, 2461-2465. 1337. High
17 142 1338. Dissociation energy of TiO(g) and the high temperature vapor-
ization and thermodynamics of the titanium oxides. Z.Trititanium pentoxide. (USA) Vapour-pressure and mass-spectrometric measurements were made on T&O, (s) contained in tungsten crucibles. The vapour-pressure measurements were obtained in the temperature range 1837”-2040” K and are used with auxiliary values to obtain enthalpy and entropy 482
18 1342. Electron energy distribution of a hollow cathode discharge in
neon-hydrogen mixture. (USSR) Electron energy distributions were measured for Ne and Ne-H, mixture discharges at a total pressure of 1.1 torr to determine the effect of adding H, to Ne in a hollow cathode discharge. V L Aphanas’eva et al, Zh Tekh Fir, 37 (2), Feb 1967, 327-329 (in Russian). 18 1343. Investigation of axial and radial inhomogeneities in helium
discharge with a hollow cathode. (USSR) Electric field, electron densities and electron energy distributions were measured in hollow cathode, helium discharges at pressures of 0.5 to 5 torr. Heterogeneities in these distributions, which are stronger at lower pressures and currents, could not be observed by optical investigations. V S Borodin et al, Zh Tekh Fiz, 37 (2), Feb 1967, 392-395 (in Russian). 18
1344. Cathode voltage drop in an arc discharge from pure metals. Part 1. (USSR) The cathode voltage drop in a low-voltage arc discharge was measured for 36 pure metals. The arc was initiated by breaking the contacts at pressures in the lO-6 torr range and with a speed of 2 cmjsec. The influence of the arc current on the cathode voltage drop was observed at currents under 10 A and also for high-melting point metals at higher currents. The relation between the value of the cathode drop and the ionizing potential of the cathode material is discussed. V E Grakov, Zh Tekh Fiz, 37 (2), Feb 1967, 396-404 (in Russian). 18 1345. Influence of the field phase on the efficiency of secondary-electron
processes in the build-up of energy yield in high power microwave electron devices. (USSR) Conditions are calculated for the avalanche increase of the number of secondary electrons near the yield of microwave energy in high power tubes or in particle accelerators. The non-resonant character
abstracts
1332-1345
16. GASES AND SOLIDS 16 1332. Ultrahigh vacuum techniques. (USA) This study was conducted on hydrogen permeation through tungsten and on the replacement of one adsorbed gas by a second from the gas phase. Significant results have been obtained on the H,-W system and some supporting work on the N,-W and H,-MO systems. R Frauenfelder et al, Rep WERE-2823-21, May 1966, (Westinghouse Corp, Pittsburgh,
Pa Research Labs). 16
The influence of oxygen in the ultrahigh vacuum range on electrical properties of CdS. (USA) Measurement of adsorption and desorption of oxygen in the range between 2.10-12 and 5.1O-8 torr and corresponding influences on photo-conductance on CdS single crystals are reported. Partial pressures were measured with a sensitive mass spectrometer located directly in front of the crystal. A typical desorption curve is given for amu 16. Effects of other gases predominant in the vacuum system such as hydrogen and carbon dioxide were also studied. K W Boer and R Schubert, Rep AROD-4461; TR-8; AD-637857, 1333.
July 1966 (Delaware
Univ, Newark,
values. These measurements were made under vacuum, initially reaching a pressure of about 5 x lO-B torr. In the mass-spectrometric measurements, three samples were placed in Knudsen crucibles and a pressure at least as low as 1O-’ torr was achieved. Two mass spectrometers were used-a high temperature, magnetic type and a time-offlight type. P G Wahleck and P W Gilles, J Chem Phys, 46 (7), 1st April 1967, 2465-2473. 17 :28 1339. Evaporator for investigation of the thermodynamic characteristics
of high-melting point materials. (USSR) Design of a Knudsen type evaporator for the MKh-1308 massspectrometer is described. The test material is placed in a tungsten crucible heated to 2700°C by an electron beam with power of up to 2kW. The working pressure is 3 x lo-’ torr. The effusion chamber can be simply adjusted during the operation. The device was proved by measu&g the sublimation temperature of La,O, in the temperature range 1490 to 2190°C. which was found to be 435&15 kcalinmol. S NBushkovich et al, iavodsk Lab, 33 (3), 1967, 376-377 (in R&an). 17 :33 1340. Liquid-helium-cooled platform
for an electron microscope.
(Japan)
Dept ofPhysic.& 16
1334. Diffusion of gases across porous media.
(USA) The basic laws of gaseous diffusion in porous media are derived from an extension of the “friction model”, without recourse to detailed kinetic theory. K S Spiegler, Ind Engng Chem, Fundamentals, 5 (4), Nov 1966, 529. 61 1335. Bonding energy of adsorbed Cs atoms with the tungsten crystal
(110) and (IOO)faces. (USSR) Isobars were measured for the adsorption of caesium on the (110) and (100) faces of tungsten single crystals and, from those values, relations between the adsorption temperature and Caesium surface concentrations were calculated. The adsorption temperature was established as 3.2 eV for the (110) face and 2.8 eV for the (100) face, for very small caesium concentrations, with a nearly linear fall of these values down to 0.8 eV at 5 x lo’* atoms per cm2 for both faces. V M Gavrilyuk et al, Fir Tverd Tela, 9 (4), Apr 1967, 1126-1128 (in Russian).
In the platform described the liquid helium flows through a thin copper pipe around the specimen holder, allowing specimen movement for observation. The holder and pipe are enclosed in a shield case kept nearly at liquid nitrogen temperature. The specimen can be exchanged by means of a conventional mechanism without breaking the vacuum. Observations of the magnetic effect in a superconducting film are described. H Watanabe and I Ishikawa, Japan J Appl Phys, 6 (I), Jan 1967,83-88. 18. GASEOUS ELECTRONICS 18 1341. Spectra of low frequency oscillations of vacuum arcs. (USSR) Arcs were produced from Mg, Zn, Cd or Bi at 10-j torr and oscillations of the arc potential were scanned at the frequency range of 20 kc/s to 30 MC/S. No noise was observed above 1 MC/S and in the steady state noise having a maximum below 200 Kc/s depends only weakly on the arc current. P E Belensov and A A Plyutto, Zh Tekh Fiz, 37 (2), Feb 1967, 3OG306 (in Russian).
17. THERMODYNAMICS
17 1336. Advanced studies on multi-layer insulation systems. (USA) Analytical and experimental studies are reported on the performance of multilayer insulation systems to reduce the heat leak rate into stored cryogenic propellants carried in space vehicles under varying environments. Experimental results showed that multilayer insulations with spacers of two or more materials are most efficient because each component can be selected to perform a specific function. Emittance stability of silver and copper coatings was highest under exposure to high humidity, carbon dioxide and salt environments. Commercial sources of good quality, low emittance shields consisted of polyester film, vacuum metallized on both sides with aluminium, silver and gold. Anon, Rep NASA-CR-54929, June 1966 (A D Little Inc, Cambridge, Massachusetts). 17 :42
temperature vaporization and thermodynamics of the titanium oxides. 1. Vaporization of the crystalline phases. (USA) The vaporization behaviour of the titanium-oxygen system has been established by experimental measurements of the change in composition of the solid residue accompanying vaporization as determined by x-ray diffraction, chemical analysis and color of sample. The solid phases studied were T&O, TiO, TieOs, T&O,, T&O,, TiBOB,TiloOlp and TiO%. Details of preparation of samples are given and all vaporizations were performed under high vacuum (usually about 1O-5 torr). P W Gilles et al, J Chem Phys, 46 (7), 1st April 1967, 2461-2465. 1337. High
17 142 1338. Dissociation energy of TiO(g) and the high temperature vapor-
ization and thermodynamics of the titanium oxides. Z.Trititanium pentoxide. (USA) Vapour-pressure and mass-spectrometric measurements were made on T&O, (s) contained in tungsten crucibles. The vapour-pressure measurements were obtained in the temperature range 1837”-2040” K and are used with auxiliary values to obtain enthalpy and entropy 482
18 1342. Electron energy distribution of a hollow cathode discharge in
neon-hydrogen mixture. (USSR) Electron energy distributions were measured for Ne and Ne-H, mixture discharges at a total pressure of 1.1 torr to determine the effect of adding H, to Ne in a hollow cathode discharge. V L Aphanas’eva et al, Zh Tekh Fir, 37 (2), Feb 1967, 327-329 (in Russian). 18 1343. Investigation of axial and radial inhomogeneities in helium
discharge with a hollow cathode. (USSR) Electric field, electron densities and electron energy distributions were measured in hollow cathode, helium discharges at pressures of 0.5 to 5 torr. Heterogeneities in these distributions, which are stronger at lower pressures and currents, could not be observed by optical investigations. V S Borodin et al, Zh Tekh Fiz, 37 (2), Feb 1967, 392-395 (in Russian). 18
1344. Cathode voltage drop in an arc discharge from pure metals. Part 1. (USSR) The cathode voltage drop in a low-voltage arc discharge was measured for 36 pure metals. The arc was initiated by breaking the contacts at pressures in the lO-6 torr range and with a speed of 2 cmjsec. The influence of the arc current on the cathode voltage drop was observed at currents under 10 A and also for high-melting point metals at higher currents. The relation between the value of the cathode drop and the ionizing potential of the cathode material is discussed. V E Grakov, Zh Tekh Fiz, 37 (2), Feb 1967, 396-404 (in Russian). 18 1345. Influence of the field phase on the efficiency of secondary-electron
processes in the build-up of energy yield in high power microwave electron devices. (USSR) Conditions are calculated for the avalanche increase of the number of secondary electrons near the yield of microwave energy in high power tubes or in particle accelerators. The non-resonant character