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716. Exploring space in the laboratory
332
Classified Abstracts 704--716
33 : 35 704. Quality capacitors in quantity production. Description of manufacturing methods at Messrs. Dubulier, with brief reference to vacuum impregnation.
thinnest carbon film measured was about 50/~ thick whilst a platinum film was measureable down to 8/~. With such thin films, unevenness of thickness affects the accuracy very markedly.
Anon., Brit. Commun. & Electronics, 9 (5), May 1962, 339.
D. Chescoe and J. S. Halliday, Nature, Land., 193 (4814), 3 Feb. 1962, 434-437.
33 : 56 705. Thermionic generators. D. A. Fraser and G. G. Isaacs, Electronic Engng, 34 (411), May 1962, 307-311. 33 706. 1.5 M e V electron microscope. Anon., Engineer, 213 (5529), 12 Jan. 1962, 96. 33 707. Field emission studies on kinetics of barium oxide on tungsten. Japan. The field emission microscope has been used to investigate the state of adsorption of barium oxide molecules deposited on tungsten by evaporation. Precautions are taken to keep the tube pressure at ultra-high vacuum. Pulse method is adopted to prevent the state of adsorption from changing with steady application of intense fields. Surface migration of adsorbed molecules over the entire surface is pronounced only above 700°C and its activation energy is about 4.6 eV. Work function decreases very rapidly for the first 0.15 layer with the rate which can be exploited quantitatively by considering the adsorbed molecules as oriented dipoles. The mean dipole moment of an adsorbed molecule is estimated to be (13.5 :k 8.1)x 10-18 e.s.u. Crystallites of barium oxide are formed when the covering factor amounts to about unity. Chemical reaction takes place between barium oxide and tungsten for temperatures above 800°C and the reaction product persists stably unless temperature is raised above 1000°C. The activation energy of the reaction is about 3.3 eV. (Author) K. N6ga, J. Phys. Soe. Japan, 17 (6), June 1962, 950-961. 33 : 51 708. High-pressure hydrogen gas target. Great Britain. A description is given of a hydrogen gas target, which has been designed to operate at a pressure of 450 lb/in. 2 and at a temperature of --70°C, to be used in studies of X-ray scattering from hydrogen using a nuclear photograph emulsion technique. The choice of material for the entrance window and the high-pressure sealing of flanges is discussed. Gaskets made of silicone rubber, of lead and indium wire, of Silastomer coated corrugated steel and, finally, hollow steel O-rings filled with an inert gas and coated with fluon were all tried, the last being found successful over the temperature range quoted. M.D.A. J. Kirk, J. Sci. Instrum., 38 (11), Nov. 1961, 439-441. 33 709. Miniature cryostat for measurements on ferromagnetics between 1.6 and 300°K, W. R. Scott and J. Crangle, J. Sci. Instrum., 38 (11), Nov. 1961, 436--438. 33 710. Improved reflexion diffraction holder for electron microscope. J. C. Henderson, J. Sci. Instrum., 38 (11), Nov. 1961, 453. 33 711. Measurement of the thickness of vacuum deposits using the electron microscope. Great Britain. The maximum specimen thickness that can be measured by means of an electron microscope is set by the current of electron penetration through the specimens. At the usual operating voltage of 100 kV, this maximum thickness is approximately 1000A for silver and 2000A, for carbon. The
W . J. S.
33 712. Charcoal absorption. U.S.S.R. Temperatures of 0.7°K are obtained by pumping away the vapour of liquid helium (boiling point 4.2°K). For this purpose diffusion pumps are normally employed. F r o m experiments carried out by members of the Ukrainian Academy of Sciences, it appears that the well-known absorption capacity of charcoal increases very greatly at temperatures below I°K and that a couple of ounces of charcoal will absorb more than 1000 litres of helium per second and, what is more remarkable, maintain this rate for over an hour. The Russian scientists describe cryostats utilising this principle. By using removable capsules containing only ½ ounce of charcoal, a temperature of 0.704°K can be maintained for ½ hour. w.J.s. Anoh., New Scientist, 16 (310), 25 Oct. 1962, 218. 33 713. Construction of a gaseous optical maser using Brewstcr angle windows. United States. A description is given of the materials, tools and techniques used to make a successful gaseous optical maser whose output windows are orientated at the Brewster angle in respect to the beam axis. (Author) D. J. Brangaecio, Rev. Sci. Instrum., 33 (9), Sept. 1962, 921-922. 33 714. Vide et ultravide dans une experience d'injection d'ions et miroirs magn~tiques. (Vacuum and ultravacuum in an experiment using ion injection magnetic mirror device). France. The vacuum system of an ion injection magnetic mirror device is described. The tube using gold gaskets is bakeable up to 400°C. Oil diffusion units give a base pressure below 10-9 m m H g . These units are arranged to provide differential pumping for local gas sources. In addition, ion pumping and getter pumping will be used. The problem of measuring transient low pressures is briefly discussed (in French). (Authors) E. Fischhoff, F. Prevot and Z. Sledziewski, Fide, (99), May/ June 1962, 195-200. 33 : 30 Metal oxide film resistors. 34.
See Abstr. No. 679.
H i g h A l t i t u d e and S p a c e T e c h n o l o g y
34 715. Effect of a vacuum on metal fatigue strength. United States. Experiments carried out on l100-H14 electropolished aluminium specimens by the National Research Corp., Cambridge, Mass., showed a very marked increase in fatigue strength (up to seven-fold) when the tests were carried out under high vacuum conditions (10 -~ torr). The results are explained by the insulating effects of oxide films which facilitate the growth of hair-cracks when the metal is tested under normal conditions. The beneficial effect of a vacuum may have important applications in the design of space vehicles, w.J.s. Anon., Chem. & Engng. News, 40 (42), 15 Oct. 1962, 62. 34 716. Exploring space in the laboratory. United States. A space simulating chamber, 3½ ft long and 18 in. in diameter has been demonstrated by engineers of the
Classified Abstracts 704--716
33 : 35 704. Quality capacitors in quantity production. Description of manufacturing methods at Messrs. Dubulier, with brief reference to vacuum impregnation.
thinnest carbon film measured was about 50/~ thick whilst a platinum film was measureable down to 8/~. With such thin films, unevenness of thickness affects the accuracy very markedly.
Anon., Brit. Commun. & Electronics, 9 (5), May 1962, 339.
D. Chescoe and J. S. Halliday, Nature, Land., 193 (4814), 3 Feb. 1962, 434-437.
33 : 56 705. Thermionic generators. D. A. Fraser and G. G. Isaacs, Electronic Engng, 34 (411), May 1962, 307-311. 33 706. 1.5 M e V electron microscope. Anon., Engineer, 213 (5529), 12 Jan. 1962, 96. 33 707. Field emission studies on kinetics of barium oxide on tungsten. Japan. The field emission microscope has been used to investigate the state of adsorption of barium oxide molecules deposited on tungsten by evaporation. Precautions are taken to keep the tube pressure at ultra-high vacuum. Pulse method is adopted to prevent the state of adsorption from changing with steady application of intense fields. Surface migration of adsorbed molecules over the entire surface is pronounced only above 700°C and its activation energy is about 4.6 eV. Work function decreases very rapidly for the first 0.15 layer with the rate which can be exploited quantitatively by considering the adsorbed molecules as oriented dipoles. The mean dipole moment of an adsorbed molecule is estimated to be (13.5 :k 8.1)x 10-18 e.s.u. Crystallites of barium oxide are formed when the covering factor amounts to about unity. Chemical reaction takes place between barium oxide and tungsten for temperatures above 800°C and the reaction product persists stably unless temperature is raised above 1000°C. The activation energy of the reaction is about 3.3 eV. (Author) K. N6ga, J. Phys. Soe. Japan, 17 (6), June 1962, 950-961. 33 : 51 708. High-pressure hydrogen gas target. Great Britain. A description is given of a hydrogen gas target, which has been designed to operate at a pressure of 450 lb/in. 2 and at a temperature of --70°C, to be used in studies of X-ray scattering from hydrogen using a nuclear photograph emulsion technique. The choice of material for the entrance window and the high-pressure sealing of flanges is discussed. Gaskets made of silicone rubber, of lead and indium wire, of Silastomer coated corrugated steel and, finally, hollow steel O-rings filled with an inert gas and coated with fluon were all tried, the last being found successful over the temperature range quoted. M.D.A. J. Kirk, J. Sci. Instrum., 38 (11), Nov. 1961, 439-441. 33 709. Miniature cryostat for measurements on ferromagnetics between 1.6 and 300°K, W. R. Scott and J. Crangle, J. Sci. Instrum., 38 (11), Nov. 1961, 436--438. 33 710. Improved reflexion diffraction holder for electron microscope. J. C. Henderson, J. Sci. Instrum., 38 (11), Nov. 1961, 453. 33 711. Measurement of the thickness of vacuum deposits using the electron microscope. Great Britain. The maximum specimen thickness that can be measured by means of an electron microscope is set by the current of electron penetration through the specimens. At the usual operating voltage of 100 kV, this maximum thickness is approximately 1000A for silver and 2000A, for carbon. The
W . J. S.
33 712. Charcoal absorption. U.S.S.R. Temperatures of 0.7°K are obtained by pumping away the vapour of liquid helium (boiling point 4.2°K). For this purpose diffusion pumps are normally employed. F r o m experiments carried out by members of the Ukrainian Academy of Sciences, it appears that the well-known absorption capacity of charcoal increases very greatly at temperatures below I°K and that a couple of ounces of charcoal will absorb more than 1000 litres of helium per second and, what is more remarkable, maintain this rate for over an hour. The Russian scientists describe cryostats utilising this principle. By using removable capsules containing only ½ ounce of charcoal, a temperature of 0.704°K can be maintained for ½ hour. w.J.s. Anoh., New Scientist, 16 (310), 25 Oct. 1962, 218. 33 713. Construction of a gaseous optical maser using Brewstcr angle windows. United States. A description is given of the materials, tools and techniques used to make a successful gaseous optical maser whose output windows are orientated at the Brewster angle in respect to the beam axis. (Author) D. J. Brangaecio, Rev. Sci. Instrum., 33 (9), Sept. 1962, 921-922. 33 714. Vide et ultravide dans une experience d'injection d'ions et miroirs magn~tiques. (Vacuum and ultravacuum in an experiment using ion injection magnetic mirror device). France. The vacuum system of an ion injection magnetic mirror device is described. The tube using gold gaskets is bakeable up to 400°C. Oil diffusion units give a base pressure below 10-9 m m H g . These units are arranged to provide differential pumping for local gas sources. In addition, ion pumping and getter pumping will be used. The problem of measuring transient low pressures is briefly discussed (in French). (Authors) E. Fischhoff, F. Prevot and Z. Sledziewski, Fide, (99), May/ June 1962, 195-200. 33 : 30 Metal oxide film resistors. 34.
See Abstr. No. 679.
H i g h A l t i t u d e and S p a c e T e c h n o l o g y
34 715. Effect of a vacuum on metal fatigue strength. United States. Experiments carried out on l100-H14 electropolished aluminium specimens by the National Research Corp., Cambridge, Mass., showed a very marked increase in fatigue strength (up to seven-fold) when the tests were carried out under high vacuum conditions (10 -~ torr). The results are explained by the insulating effects of oxide films which facilitate the growth of hair-cracks when the metal is tested under normal conditions. The beneficial effect of a vacuum may have important applications in the design of space vehicles, w.J.s. Anon., Chem. & Engng. News, 40 (42), 15 Oct. 1962, 62. 34 716. Exploring space in the laboratory. United States. A space simulating chamber, 3½ ft long and 18 in. in diameter has been demonstrated by engineers of the