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Production of surface electrostatic charging on dielectrics cleaved in vacuum
Classified
abstracts
2072-2083
control
coating
35. IMPREGNATION
WCLIU~
system
3.5 2078. Vacuum impregnation of parts of rotating electric machines without the use of solvents. (Czechoslovakia) A process of vacuum impregnation of motor bindings by use of solvent-free impregnation materials is described. The solvent-free compound is prepared only from domestically avnilablc materials and is the subject of a patent application. M Ambroz, Elektrotedr Ohzor, 56 (8). :lyq 1Y67. 446 44X Ii/r (~:c~c~lr).
programme. Subjects discussed are: an ultrahigh used in support of simulation testing, a pressure arc facility, and spectral irradi&e measurements of various light sources. R McIntosh. Ren NASA-TM-X-55735: X-713-67-73. Feb 1967 (NASA Goddard Space ‘Flight Cetrter. Greenhelt. Mar~~lantl). 34 2072. A nitrogen plasma. (USA) To simulate the space environment encountered by a satellite in terms of temperature. vacuum. and solar flux, a model nitrogen atmosphere was investigated. Parameters pertinent to high altitude charged particle regions are graphed. Technical details are given on beam neutralization, general plasma diagnosis and the spherical probe. It is concluded that the electron-bombardment source is capable of producing a steady nitrogen plasma of varying density over a considerable volume. J H Kinnier, Rep NASA-TM-X-55742, X-700-67-94, 1967, 359-372 (NASA, Gotfhrtl Space Flight Center, Gree~helt. Mar.dantl). 34 2073. An analysis of results of thermal-vacuum tests on OGO experiments. (USA) Simulated space tests conducted on experiments for the Orbiting Geophysical Observatory have been reviewed and analyzed. The 374 tests were examined and summarized for the effects of test time, thermal level. sequence, phase, experimenter, and model on the numbers and time distribution of failures. N E Lucas and A R Timmins, Rep NASA-TM-X-55748 ; X-326-67-75, Feh 1967 (NASA, Goddard Space Flight Ceuter, Greenbelt, Maryland). 34 2074. Properties of powder ground in ultrahigh vacuum. (USA) An investigation was conducted into the properties of lunar soil by simulating the comminution of the rock in ultrahigh vacuum. Previous simulation studies are reviewed and the need for vacuum comminution is discussed. An apparatus was constructed for pulverizing the rock in ultrahigh vacuum to permit determination of the properties of powders produced with atomically clean particle surfaces. Basalt powder was produced while maintaining pressures in the range of 10 Dto 10vq torr: this required extensive rock baking prior to comminution. Comparative data arc presented on the properties and hehaviour of basalt powder ground in vacuum and in air. I’ Blum et al. Rep h’A.SA-CR-66276, .Mtrrch I967 (Nrr/ionc7/ Res Corp. Carlrhritl,w. ,~Itr.v.~ot~lrrr.vc~tr.~ ). 34 2075. Investigation of the adhesion of metals in ultrahigh vacuum. (USA) Adhesion-friction tests were conducted at vacuum levels below I .. IO D torr for annealed copper, titanium and tungsten. Prior to contact under loads up to 1000 Ibs mating cup-and-cone shaped specimens were subjected to xenon ion gas bombardment or rotational self-abrasion. Subsequently, residual shear torque. frictional torque and normal adhesion forces were measured. M J Hordon and J R Roehring, Rep NASA-CR-66279, Dee 1966 ( National Research C’orp, Cmh?c/ge, ,~~assachrrset?.s). 34 2076. Adhesional vacuum formed silicate surfaces. (USA) The possible adhesional behaviour of lunar silicates was investigated by determining the forces between air-formed (or contaminated) and vacuum-formed (clean) surfaces. For the air-formed surfaces, the adhesion force was generally relatively low, in no case exceeding 5 Y lo2 dynes. For the vacuum-formed surfaces it was found that the adhesion force was much larger and that a considerable amount of surface electrostatic charging was produced during surface formation. The results indicate that the range of lunar adhesional phenomena can be quite large. J A Ryan and M B Baker, Rep h’.4S.4-(‘R-83647; Marclr lY67 (Douglas .4iwrq/i Co. Smttr Mouica, Cal(/iw/riu). 34 2077. Space environments: their effects on spacecraft design. (Netherlands) The space environments of major importance in spacecraft design arc considered from the point of view of the technical problems presented. The effects these environments produce on a spacecraft in orbit are discussed in some details. The problems of laboratory simulation of these space environments are considered; in particular, the combination of vacuum, the heat sink of space and thermal radiation sources. S L Entres, Rep ESRO-TM-47. Nov 1966 (European Space Techrro1og.v Center, Noorchijk, Netf7erlanrl.s~. 682
36. DRYING,
AND POTTING
DEGASSlNG
AND CONCENTRATION
?h : 41 2079. The dehydration of porous glass. ( USA) A microbalance was used to follow the kinetics of dehydration 01 porous glass in vacua at constant temperatures from 25 to X00 C. The kinetics of water sorption and dcsorption by the degassed surfaces were measured. It was found that physically adsorbed water as well as some tightly-bound water could bc removed at 25 C. Degassing above 600‘C produces surfaces containing isolated hydroxyls. The amount of water retained after a sorption-desorption cycle is a maximum with samples degassed near 300 C. It is proposed that geminal hydroxyls responsible for this maximum are destroyed. The percentage of the sorbed water which is retained increases with samples degassed above 6OO’C. This effect is produced by horon migrating to the surface of the glass. M J D Low and N Ramasuhramanian, Rep TR-5: AD-647303, Z\furc~/! 1967(Rutgers Univ, New Brwu~vick, New Jew,>,). 37. METALLURGY, CHEMISTRY
INORGANIC
CHEMISTRY,
ANALYTICAL
37 2080. Cleaning a (0001) beryllium surface. (USA) The requirements for obtaining a clean surface of a bt’ryllium single crystal were investigated by measuring the low-cncrgy electron diffraction pattern of the surface. It was found that a clean surface is obtained either by heating at IOOO‘C for 5 minutes or by sputtering the surface for 30 minutes with 1000 eV argon ions. Heating the crystal to less than 800°C produced no diffraction pattern indicating little if any cleaning. R 0 Adams, Mater Res Bull. 2 (7). J/I/J. 1967. 64’). J7 2081. Vacuum ultraviolet research. (USA) Discusses some applications of vacuum LIV radiation to basic research problems, particularly the study of the structure and optical propcrties of gases and solids. J AR Samson, Appl Opfics, 6 (3), Maw/l 1967, 403 40X. 37 : IX 2082. Production of surface electrostatic charging on dielectrics cleaved in vacuum. (USA) The formation of considerable surface charging for silicates clcavcd at 10 I0 torr was observed. This charging is stable, apparently nonuniform on a macroscopic scale, persists to 10 ’ torr and contributes significantly to the adhesion. Additional observations show that the resultant force field is of such a nature that it can rotate the sample into alignment, and that while on some occasions the samples are attracted to any metal in the vicinity, on other occasions there is no attraction. This paper considers mechanisms that could be rcsponsible for this charging. A number of theoretical models are discussed bv which an electric polarization can be induced into non-piezoelectric dielectric crystals. J J Grossman, Rep NASA-CR-83647: .I-830-BBK3-37: QPR-I I. .%iay 1967 ( Darr&~sAiwrqft Co. San/a Morrictr. Cdifiwria). 37 2083. Synthesis of higher order hydrocarbons on hot tungsten iilaments. (USA) The study used a quadrupole mass spectrometer of sensitivity IO ” torr (N? equivalent) to show the synthesis of acctylcne, cthanc. propylene and propane from methane on a hot tungsten lilament. The relationship between the partial pressures of these hydrocarbons and the filament temperature was investigated. The constancy of the product composition for a given temperature at two partial pressures of methane is also demonstrated. It is concluded that the mcasurement of total pressure in the ultrahigh vacuum regions by hot filament gauges may be erroneous due to this kind of synthesis. H Shapiro and B N Paxson, Rep &‘,4SA-TN-D-3906, .4pril lY67 (NASA. Goddard Space Flight Center. Grec~trhell. Rfar~hd).
abstracts
2072-2083
control
coating
35. IMPREGNATION
WCLIU~
system
3.5 2078. Vacuum impregnation of parts of rotating electric machines without the use of solvents. (Czechoslovakia) A process of vacuum impregnation of motor bindings by use of solvent-free impregnation materials is described. The solvent-free compound is prepared only from domestically avnilablc materials and is the subject of a patent application. M Ambroz, Elektrotedr Ohzor, 56 (8). :lyq 1Y67. 446 44X Ii/r (~:c~c~lr).
programme. Subjects discussed are: an ultrahigh used in support of simulation testing, a pressure arc facility, and spectral irradi&e measurements of various light sources. R McIntosh. Ren NASA-TM-X-55735: X-713-67-73. Feb 1967 (NASA Goddard Space ‘Flight Cetrter. Greenhelt. Mar~~lantl). 34 2072. A nitrogen plasma. (USA) To simulate the space environment encountered by a satellite in terms of temperature. vacuum. and solar flux, a model nitrogen atmosphere was investigated. Parameters pertinent to high altitude charged particle regions are graphed. Technical details are given on beam neutralization, general plasma diagnosis and the spherical probe. It is concluded that the electron-bombardment source is capable of producing a steady nitrogen plasma of varying density over a considerable volume. J H Kinnier, Rep NASA-TM-X-55742, X-700-67-94, 1967, 359-372 (NASA, Gotfhrtl Space Flight Center, Gree~helt. Mar.dantl). 34 2073. An analysis of results of thermal-vacuum tests on OGO experiments. (USA) Simulated space tests conducted on experiments for the Orbiting Geophysical Observatory have been reviewed and analyzed. The 374 tests were examined and summarized for the effects of test time, thermal level. sequence, phase, experimenter, and model on the numbers and time distribution of failures. N E Lucas and A R Timmins, Rep NASA-TM-X-55748 ; X-326-67-75, Feh 1967 (NASA, Goddard Space Flight Ceuter, Greenbelt, Maryland). 34 2074. Properties of powder ground in ultrahigh vacuum. (USA) An investigation was conducted into the properties of lunar soil by simulating the comminution of the rock in ultrahigh vacuum. Previous simulation studies are reviewed and the need for vacuum comminution is discussed. An apparatus was constructed for pulverizing the rock in ultrahigh vacuum to permit determination of the properties of powders produced with atomically clean particle surfaces. Basalt powder was produced while maintaining pressures in the range of 10 Dto 10vq torr: this required extensive rock baking prior to comminution. Comparative data arc presented on the properties and hehaviour of basalt powder ground in vacuum and in air. I’ Blum et al. Rep h’A.SA-CR-66276, .Mtrrch I967 (Nrr/ionc7/ Res Corp. Carlrhritl,w. ,~Itr.v.~ot~lrrr.vc~tr.~ ). 34 2075. Investigation of the adhesion of metals in ultrahigh vacuum. (USA) Adhesion-friction tests were conducted at vacuum levels below I .. IO D torr for annealed copper, titanium and tungsten. Prior to contact under loads up to 1000 Ibs mating cup-and-cone shaped specimens were subjected to xenon ion gas bombardment or rotational self-abrasion. Subsequently, residual shear torque. frictional torque and normal adhesion forces were measured. M J Hordon and J R Roehring, Rep NASA-CR-66279, Dee 1966 ( National Research C’orp, Cmh?c/ge, ,~~assachrrset?.s). 34 2076. Adhesional vacuum formed silicate surfaces. (USA) The possible adhesional behaviour of lunar silicates was investigated by determining the forces between air-formed (or contaminated) and vacuum-formed (clean) surfaces. For the air-formed surfaces, the adhesion force was generally relatively low, in no case exceeding 5 Y lo2 dynes. For the vacuum-formed surfaces it was found that the adhesion force was much larger and that a considerable amount of surface electrostatic charging was produced during surface formation. The results indicate that the range of lunar adhesional phenomena can be quite large. J A Ryan and M B Baker, Rep h’.4S.4-(‘R-83647; Marclr lY67 (Douglas .4iwrq/i Co. Smttr Mouica, Cal(/iw/riu). 34 2077. Space environments: their effects on spacecraft design. (Netherlands) The space environments of major importance in spacecraft design arc considered from the point of view of the technical problems presented. The effects these environments produce on a spacecraft in orbit are discussed in some details. The problems of laboratory simulation of these space environments are considered; in particular, the combination of vacuum, the heat sink of space and thermal radiation sources. S L Entres, Rep ESRO-TM-47. Nov 1966 (European Space Techrro1og.v Center, Noorchijk, Netf7erlanrl.s~. 682
36. DRYING,
AND POTTING
DEGASSlNG
AND CONCENTRATION
?h : 41 2079. The dehydration of porous glass. ( USA) A microbalance was used to follow the kinetics of dehydration 01 porous glass in vacua at constant temperatures from 25 to X00 C. The kinetics of water sorption and dcsorption by the degassed surfaces were measured. It was found that physically adsorbed water as well as some tightly-bound water could bc removed at 25 C. Degassing above 600‘C produces surfaces containing isolated hydroxyls. The amount of water retained after a sorption-desorption cycle is a maximum with samples degassed near 300 C. It is proposed that geminal hydroxyls responsible for this maximum are destroyed. The percentage of the sorbed water which is retained increases with samples degassed above 6OO’C. This effect is produced by horon migrating to the surface of the glass. M J D Low and N Ramasuhramanian, Rep TR-5: AD-647303, Z\furc~/! 1967(Rutgers Univ, New Brwu~vick, New Jew,>,). 37. METALLURGY, CHEMISTRY
INORGANIC
CHEMISTRY,
ANALYTICAL
37 2080. Cleaning a (0001) beryllium surface. (USA) The requirements for obtaining a clean surface of a bt’ryllium single crystal were investigated by measuring the low-cncrgy electron diffraction pattern of the surface. It was found that a clean surface is obtained either by heating at IOOO‘C for 5 minutes or by sputtering the surface for 30 minutes with 1000 eV argon ions. Heating the crystal to less than 800°C produced no diffraction pattern indicating little if any cleaning. R 0 Adams, Mater Res Bull. 2 (7). J/I/J. 1967. 64’). J7 2081. Vacuum ultraviolet research. (USA) Discusses some applications of vacuum LIV radiation to basic research problems, particularly the study of the structure and optical propcrties of gases and solids. J AR Samson, Appl Opfics, 6 (3), Maw/l 1967, 403 40X. 37 : IX 2082. Production of surface electrostatic charging on dielectrics cleaved in vacuum. (USA) The formation of considerable surface charging for silicates clcavcd at 10 I0 torr was observed. This charging is stable, apparently nonuniform on a macroscopic scale, persists to 10 ’ torr and contributes significantly to the adhesion. Additional observations show that the resultant force field is of such a nature that it can rotate the sample into alignment, and that while on some occasions the samples are attracted to any metal in the vicinity, on other occasions there is no attraction. This paper considers mechanisms that could be rcsponsible for this charging. A number of theoretical models are discussed bv which an electric polarization can be induced into non-piezoelectric dielectric crystals. J J Grossman, Rep NASA-CR-83647: .I-830-BBK3-37: QPR-I I. .%iay 1967 ( Darr&~sAiwrqft Co. San/a Morrictr. Cdifiwria). 37 2083. Synthesis of higher order hydrocarbons on hot tungsten iilaments. (USA) The study used a quadrupole mass spectrometer of sensitivity IO ” torr (N? equivalent) to show the synthesis of acctylcne, cthanc. propylene and propane from methane on a hot tungsten lilament. The relationship between the partial pressures of these hydrocarbons and the filament temperature was investigated. The constancy of the product composition for a given temperature at two partial pressures of methane is also demonstrated. It is concluded that the mcasurement of total pressure in the ultrahigh vacuum regions by hot filament gauges may be erroneous due to this kind of synthesis. H Shapiro and B N Paxson, Rep &‘,4SA-TN-D-3906, .4pril lY67 (NASA. Goddard Space Flight Center. Grec~trhell. Rfar~hd).