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Solar-energy materials preparation techniques
Classified
abstracts
1493-I
501
34 1493. Spcctroradiomctric calibration techniques in the far ultraviolet: a stable emission source for the Lyman bands of molecular bydrogen. (USA) The problems associated with making accurate spectroradiomctric measurements in the far uv region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo I7 far uv spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable uv light sources, was developed to calibrate the Apollo I7 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations betvveen about I200 A and I700 A were performed with an absolute accuracy of * 10yO. The light source, which was designed to provide a very stable light output. is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder. Individual emission lines of the Lyman molecular band system of HZ are used for calibration purposes. The lamp also copiously emits the 1215.7-A line (Lyz) ofatomic hydrogen. W G Fastie and D E Kerr, App/ Opt, 14 (9), l975,2133-2142.
34:45 1494. Bonded electrodes for use on the external surfaces of spacecraft. (USA) A new bonding process is described which is suitable for applying electrodes to the external surfaces of spacecraft and sounding rockets. A polyimide material containing small, uniform glass spheres provides the necessary insulation and mechanical strength. The bonded electrodes are simple to construct and are shown to have good electrical, vacuum, and thermal properties. B R F Kendall and J 0 Weeks, Rev Sci /m/rttttt, 46 (8). 1975, I l23-
1125.
35.
PROCESSING
OF
MATERIALS
35 1495. Outgassing of vacuum materials-I.
(GB) In the absence of leaks, the outgassing of the chamber walls determines the lowest pressure obtainable in a vacuum system. Thus the selection of the materials of construction has a marked influence on the system’s performance. Outgassing occurs by desorption from the surface and diffusion from the bulk material. Part I explores these processes and how they affect the pumpdown curve of the system.
R J Elsey, l’uc~~~~~~r, 25 (7). 1975, 299-306. 1496. Electromagnetic Wf+V
levitation facility incorporating
35 electron beam.
An electromagnetic levitation apparatus incorporating an electron beam for auxiliary heating and melting has been developed for experiments on containerless vacuum purification and undercooled solidification of high melting materials. Stable levitation of 10-g specimens of molten tungsten has been achieved and a variety of containerless solidification experiments ia being performed, including pure polycrystalline castings and single tungsten crystals grown from the undercooled levitated melts. G Wouch et al, Reu Sci It~strutn, 46 (S), 1975, 1122-l 123.
will require a fabrication rate of greater than I .8 )’ IO’ rnz (50 square milts) per year. Present high-volume deposition capabilities are reviewed, and it is shown that for some types of deposition, namely electrodeposition, e-beam vacuum evaporation, and possibly sputter deposition, facilities exist which approach the desired volumes. D M Mattox,J l’uc Sci Tec/aro/, I2 (5), 1975, 1023-1031.
36. VACUUM STUDIES
1NSTRUMENTATlON
FOR
SURFACE
36 1498. SORBAS: an apparatus for investigating ion scattering from surfaces at energies 100-2000 eV. (GB) An uhv apparatus is described which allows energy analysis of low energy rare gas ions backscattered from surfaces in the energy range from IO0 to 2000 eV and in a large range of scattering angles. Surface composition is measured by ion scattering and Auger electron spectroscopy. Surface structure of monocrystalline samples is evaluated by LEED. Examples of surface composition analysis and ion impact desorption are given. (Germany) E Taglauer et al, J P/~Ju E: Rcu Sciettl Itt.~~ttt, 8 (9). 1975, 768-772 (iti Gerttmt).
1499. Low energy ion backscattering spectroscopy (ISS) commercial Auger cylindrical mirror analyser (CMA). (USA)
36 with a
A commercial Auger CMA is used alternately for AES and ISS experiments by simple changes of the deflection and secondary electron multiplier voltages. A retractable movable aperture between CMA and target defines the scattering angle. ISS measurements less than 6’A of all ions entering the CMA are scattered out of the plane of incidence of the ion beam. Thus no aperture is necessary for routine investigations which allows rapid switchover from AES to ISS. H Niehus and E Bauer, Reu Sci Ins/runt, 46 (9), 1975, 1275-l 277.
36 1500. Surface composition and morphology vs secondary-electron yield of Be-Cu dynodes. (USA) Auger electron spectroscopic techniques were used to monitor the surface composition of a beryllium
IV. Materials and techniques vacuum technology
used
in
35
1497. Solar-energy
materials preparation techniques. (USA)
The application of materials to the thermal control of structures, photothermal/electrical conversion, and photovoltaic conversion are reviewed. Applications include solar and infrared reflectors, optical bulk semiconductor materials, filters, transparent conductors, semiconductor films, and selective solar absorbers. The use of thin films in many conservation and photothermal applications is presently economical, but the economics of photothermal/electrical and photovoltaic conversion is still being investigated. The means of obtaining selective solar absorbers which have a high solar absorptance and low ir emittance are discussed, and specific data on an electrodeposited black-chrome selective absorber is presented. It is shown that solar-electric generating plants must be constructed at a cost of about $50/m* to be competitive with other electrical generating plants, and that a meaningful impact on the electrical energy economy
42. GLASS, PLASTICS. CEMENTS,
CERAMICS, ELASTOMERS. LACQUERS,
REFRACTORY WAXES. PAINTS,
OXIDES, LUBRICANTS.
6x3
42 1501. Memory switching in films of oxide glasses containing bismuth. KW Negative resistance and memory switching effects have been observed in NaZO-BZOa-BiZO&OZ glass films of thicknesses between 2 and 14 pm. The off-state resistance could possibly arise due to electron hopping between conducting islands of bismuth. The on-state characteristics suggest that the memory action might be due to the formation of metallic filaments between the bismuth particles. (India) D Chakravorty and C S Murphy, J Plrys D: Appl Phys, 8 (13), 1975, Ll62-Ll65.
87
abstracts
1493-I
501
34 1493. Spcctroradiomctric calibration techniques in the far ultraviolet: a stable emission source for the Lyman bands of molecular bydrogen. (USA) The problems associated with making accurate spectroradiomctric measurements in the far uv region are sketched briefly. The equipment and methods that were developed for providing absolute sensitivity calibration of an Apollo I7 far uv spectrometer are described. The absolute reference standards were photoelectric diodes calibrated at the National Bureau of Standards. A complete vacuum optical facility, which included a premonochromator and stable uv light sources, was developed to calibrate the Apollo I7 instrument, and it has been used for a number of other tasks. Absolute radiometric calibrations betvveen about I200 A and I700 A were performed with an absolute accuracy of * 10yO. The light source, which was designed to provide a very stable light output. is a low-pressure molecular hydrogen lamp in which the pressure is stabilized by thermal control of uranium hydride powder. Individual emission lines of the Lyman molecular band system of HZ are used for calibration purposes. The lamp also copiously emits the 1215.7-A line (Lyz) ofatomic hydrogen. W G Fastie and D E Kerr, App/ Opt, 14 (9), l975,2133-2142.
34:45 1494. Bonded electrodes for use on the external surfaces of spacecraft. (USA) A new bonding process is described which is suitable for applying electrodes to the external surfaces of spacecraft and sounding rockets. A polyimide material containing small, uniform glass spheres provides the necessary insulation and mechanical strength. The bonded electrodes are simple to construct and are shown to have good electrical, vacuum, and thermal properties. B R F Kendall and J 0 Weeks, Rev Sci /m/rttttt, 46 (8). 1975, I l23-
1125.
35.
PROCESSING
OF
MATERIALS
35 1495. Outgassing of vacuum materials-I.
(GB) In the absence of leaks, the outgassing of the chamber walls determines the lowest pressure obtainable in a vacuum system. Thus the selection of the materials of construction has a marked influence on the system’s performance. Outgassing occurs by desorption from the surface and diffusion from the bulk material. Part I explores these processes and how they affect the pumpdown curve of the system.
R J Elsey, l’uc~~~~~~r, 25 (7). 1975, 299-306. 1496. Electromagnetic Wf+V
levitation facility incorporating
35 electron beam.
An electromagnetic levitation apparatus incorporating an electron beam for auxiliary heating and melting has been developed for experiments on containerless vacuum purification and undercooled solidification of high melting materials. Stable levitation of 10-g specimens of molten tungsten has been achieved and a variety of containerless solidification experiments ia being performed, including pure polycrystalline castings and single tungsten crystals grown from the undercooled levitated melts. G Wouch et al, Reu Sci It~strutn, 46 (S), 1975, 1122-l 123.
will require a fabrication rate of greater than I .8 )’ IO’ rnz (50 square milts) per year. Present high-volume deposition capabilities are reviewed, and it is shown that for some types of deposition, namely electrodeposition, e-beam vacuum evaporation, and possibly sputter deposition, facilities exist which approach the desired volumes. D M Mattox,J l’uc Sci Tec/aro/, I2 (5), 1975, 1023-1031.
36. VACUUM STUDIES
1NSTRUMENTATlON
FOR
SURFACE
36 1498. SORBAS: an apparatus for investigating ion scattering from surfaces at energies 100-2000 eV. (GB) An uhv apparatus is described which allows energy analysis of low energy rare gas ions backscattered from surfaces in the energy range from IO0 to 2000 eV and in a large range of scattering angles. Surface composition is measured by ion scattering and Auger electron spectroscopy. Surface structure of monocrystalline samples is evaluated by LEED. Examples of surface composition analysis and ion impact desorption are given. (Germany) E Taglauer et al, J P/~Ju E: Rcu Sciettl Itt.~~ttt, 8 (9). 1975, 768-772 (iti Gerttmt).
1499. Low energy ion backscattering spectroscopy (ISS) commercial Auger cylindrical mirror analyser (CMA). (USA)
36 with a
A commercial Auger CMA is used alternately for AES and ISS experiments by simple changes of the deflection and secondary electron multiplier voltages. A retractable movable aperture between CMA and target defines the scattering angle. ISS measurements less than 6’A of all ions entering the CMA are scattered out of the plane of incidence of the ion beam. Thus no aperture is necessary for routine investigations which allows rapid switchover from AES to ISS. H Niehus and E Bauer, Reu Sci Ins/runt, 46 (9), 1975, 1275-l 277.
36 1500. Surface composition and morphology vs secondary-electron yield of Be-Cu dynodes. (USA) Auger electron spectroscopic techniques were used to monitor the surface composition of a beryllium
IV. Materials and techniques vacuum technology
used
in
35
1497. Solar-energy
materials preparation techniques. (USA)
The application of materials to the thermal control of structures, photothermal/electrical conversion, and photovoltaic conversion are reviewed. Applications include solar and infrared reflectors, optical bulk semiconductor materials, filters, transparent conductors, semiconductor films, and selective solar absorbers. The use of thin films in many conservation and photothermal applications is presently economical, but the economics of photothermal/electrical and photovoltaic conversion is still being investigated. The means of obtaining selective solar absorbers which have a high solar absorptance and low ir emittance are discussed, and specific data on an electrodeposited black-chrome selective absorber is presented. It is shown that solar-electric generating plants must be constructed at a cost of about $50/m* to be competitive with other electrical generating plants, and that a meaningful impact on the electrical energy economy
42. GLASS, PLASTICS. CEMENTS,
CERAMICS, ELASTOMERS. LACQUERS,
REFRACTORY WAXES. PAINTS,
OXIDES, LUBRICANTS.
6x3
42 1501. Memory switching in films of oxide glasses containing bismuth. KW Negative resistance and memory switching effects have been observed in NaZO-BZOa-BiZO&OZ glass films of thicknesses between 2 and 14 pm. The off-state resistance could possibly arise due to electron hopping between conducting islands of bismuth. The on-state characteristics suggest that the memory action might be due to the formation of metallic filaments between the bismuth particles. (India) D Chakravorty and C S Murphy, J Plrys D: Appl Phys, 8 (13), 1975, Ll62-Ll65.
87