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3832. Vacuum breakdown from electroluminescent impurities on metallic cathode surfaces
Classified abstracts 3 8 2 8 - 3 8 6 5 Classified abstracts 3 8 2 8 - 3 8 3 7 on this page
Editor's n o t e
The label immediately following the title of each item denotes country or origin of publication, and at the end of each abstract indicates country of origin of work (where known).
I. G e n e r a l v a c u u m s c i e n c e and engineering 10. KINETIC T H E O R Y OF GASES 10 3828. The approximate calculation of transmission probabilities for the conductance of tubulations in the molecular flow regime. (GB) Simple empirical expressions are given to calculate the transmission probability W (Clausing-factor) of cylindrical orifices and tubes. One expression covers the range for the ratio length/diameter × from 0.01 to 17, another from 11 to 100. The error is within =t=0.5~o with respect to the exact values from Nawyn and Meyer. (Germany) H Henning, Vacuum, 28 (3), 1978, 151-152.
11. GASES A N D SOLIDS II 3829. Quantitative determination of the ESD ion angular and energy distribution: oxygen on W(100). (Germany) The ion angular distribution of the electron stimulated desorbed ions (ESDIAD) of O/W(100) shows dramatic anisotropies. ESDIAD as well as the energy distribution (ESDED) of desorbed 0 + ions were measured. In addition the W(100) surface could be characterized in situ with AES and LEED. Neither ESDIAD nor ESDED were much affected by the change of the angle of incidence of the primary electrons. Surface reconstruction and faceting of O/W(100) results in characteristic changes in ESDIAD and ESDED which could be understood in terms of a simple model. H Niehus, Vakuum-Tech, 27 (5), 1978, 136-140 (in German). 11 3830. Photoelectron spectroscopy of nitrogen adsorbed on tungsten (110). (Germany) Nitrogen layers adsorbed on W(110) at 100 K have been investigated by XPS, UPS and XAES. We conclude from the results that only one molecular adsorbed N2 species exists and that the N2 molecules most probably stand upright on the surface. The core level spectra are characterized by very intense satellites, which is understandable in terms of very recent theories and can be attributed to the very weak adsorption bond. By comparision of UPS and XPS valence band spectra the two adsorbate peaks found can be assigned to levels which are derived from the 1o,, and the ~',, + 2% levels of the Nz molecule. The adsorption kinetics is characterized by a constant sticking coefficient up to saturation. J C Fuggle and D Menzel, Vakuum-Tech, 27 (5), 1978, 13.0-135 (in German). I1 3831. A thermal evolution study of the trapping and release of inert gases in nickel. (GB) A series of experiments is reported on the trapping and release of the inert gases neon and argon at low energies ( < 3 keV) in a nickel (111) monocrystal using thermal evolution mass spectrometry. The results of this study and some further experiments performed for comparision purposes using the light ion helium as the implanted species indicated that the implanted gas distribution and fluence are the parameters which primarily define the form of the observed spectra. The damaging capability of the ion, which is a function of its energy and mass, appears to be of importance only in that it determines the total amount of gas retained in the target after implantation, but does not influence the overall form of the spectra. Several peaks have been observed in the spectra and possible mechanisms to explain these peaks are proposed. S E Donnelly, Vacuum, 28 (4), 1978, 163-171.
12. GASEOUS ELECTRONICS 12 3832. Vacuum breakdown from electroluminescent impurities on metallic cathode surfaces. (GB) Electroluminescent spots have been observed on the surface of OFHC and high purity copper, molybdenum, stainless steel type EN58B and HSI5 duraluminium electrodes. The intensity of the light obeys the AIfrey-Taylor relationship for electroluminescence and discharges have been observed from within the light emitting regions. A positive correlation was found to exist between the occurrence of a discharge flare and breakdown of the gap. It is suggested that breakdown was initiated by a trigger discharge at an impurity that had become charged by electron emission from its surface. R E Hurley and P J Dooley, Vacuum, 28 (3), 1978, 147-149. 12 3833. Generation and measurement of subpicosecond electron beam pulses. (USA) The generation and measurement of subpicosecond electron beam pulses by the transverse-longitudinal combination gate system is described. The temporal property of the pulse gate is analysed with the help of the longitudinal emittance diagram. Close agreement has been obtained between the calculated pulse width and the observed one which was measured by the Lissajous's figure method. A beam pulse of 0.2 ps (FWHM) was produced. (Japan) T Hosokawa et al, Rev scient h~strum, 49 (5), 1978, 627-629. 12 3834. Secondary particle collection in ion implantation dose measurement. (USA) The measurement of ion implantation doses in the presence of secondary ions and electrons emitted from the target is discussed. A circuit and electrode geometry for obtaining accurate ion beam current measurements in the presence of both positive and negative secondary particles is presented. D M Jamba, Rev scient lnstrum, 49 (5), 1978, 637-638. 12 3835. Pressure dependence of the rise time of laser-triggered spark gaps. (GB) A laser-triggered spark gap has been built to generate fast pulses which are applied to an electro-optic switch. The LTSG has been designed to give a minimum rise time for a certain gap setting. It has been shown that the parameters, voltage and pressure, which are determined theoretically to give this minimum rise time are in reasonable agreement with the practically measured values. J C Sott and A W Palmer, J Phys E: Sci lnstrum, 11 (5), 1978, 495496. 12 3836. Enrichment of hydrogen isotopes using the low-temperature glow-discharge technique. (USA) Deuterium enrichments are reported for flowing methane/hydrogen mixtures subjected to a glow discharge at low temperatures. Dependence of the enrichment factor on initial D/H ratios, flow rates, system pressure, discharge energies and translational temperature of the reacting gas mixture was studied. In addition to enrichment measurements, details of the estimate of energy requirements for enrichment of deuterium from natural abundance are included. C E Geosling and T J Manuccia, J appl Phys, 49 (5), 1978, 2605-2610. 12 3837. Excitation processes in a Pb--He discharge. (USA) Measurements of the emission from Pb + in the afterglow of a pulsed H e : P b discharge in a large-bore tube and of the intensities of Pb + and Pb emission lines in a small-bore dc discharge tube have been 85
Editor's n o t e
The label immediately following the title of each item denotes country or origin of publication, and at the end of each abstract indicates country of origin of work (where known).
I. G e n e r a l v a c u u m s c i e n c e and engineering 10. KINETIC T H E O R Y OF GASES 10 3828. The approximate calculation of transmission probabilities for the conductance of tubulations in the molecular flow regime. (GB) Simple empirical expressions are given to calculate the transmission probability W (Clausing-factor) of cylindrical orifices and tubes. One expression covers the range for the ratio length/diameter × from 0.01 to 17, another from 11 to 100. The error is within =t=0.5~o with respect to the exact values from Nawyn and Meyer. (Germany) H Henning, Vacuum, 28 (3), 1978, 151-152.
11. GASES A N D SOLIDS II 3829. Quantitative determination of the ESD ion angular and energy distribution: oxygen on W(100). (Germany) The ion angular distribution of the electron stimulated desorbed ions (ESDIAD) of O/W(100) shows dramatic anisotropies. ESDIAD as well as the energy distribution (ESDED) of desorbed 0 + ions were measured. In addition the W(100) surface could be characterized in situ with AES and LEED. Neither ESDIAD nor ESDED were much affected by the change of the angle of incidence of the primary electrons. Surface reconstruction and faceting of O/W(100) results in characteristic changes in ESDIAD and ESDED which could be understood in terms of a simple model. H Niehus, Vakuum-Tech, 27 (5), 1978, 136-140 (in German). 11 3830. Photoelectron spectroscopy of nitrogen adsorbed on tungsten (110). (Germany) Nitrogen layers adsorbed on W(110) at 100 K have been investigated by XPS, UPS and XAES. We conclude from the results that only one molecular adsorbed N2 species exists and that the N2 molecules most probably stand upright on the surface. The core level spectra are characterized by very intense satellites, which is understandable in terms of very recent theories and can be attributed to the very weak adsorption bond. By comparision of UPS and XPS valence band spectra the two adsorbate peaks found can be assigned to levels which are derived from the 1o,, and the ~',, + 2% levels of the Nz molecule. The adsorption kinetics is characterized by a constant sticking coefficient up to saturation. J C Fuggle and D Menzel, Vakuum-Tech, 27 (5), 1978, 13.0-135 (in German). I1 3831. A thermal evolution study of the trapping and release of inert gases in nickel. (GB) A series of experiments is reported on the trapping and release of the inert gases neon and argon at low energies ( < 3 keV) in a nickel (111) monocrystal using thermal evolution mass spectrometry. The results of this study and some further experiments performed for comparision purposes using the light ion helium as the implanted species indicated that the implanted gas distribution and fluence are the parameters which primarily define the form of the observed spectra. The damaging capability of the ion, which is a function of its energy and mass, appears to be of importance only in that it determines the total amount of gas retained in the target after implantation, but does not influence the overall form of the spectra. Several peaks have been observed in the spectra and possible mechanisms to explain these peaks are proposed. S E Donnelly, Vacuum, 28 (4), 1978, 163-171.
12. GASEOUS ELECTRONICS 12 3832. Vacuum breakdown from electroluminescent impurities on metallic cathode surfaces. (GB) Electroluminescent spots have been observed on the surface of OFHC and high purity copper, molybdenum, stainless steel type EN58B and HSI5 duraluminium electrodes. The intensity of the light obeys the AIfrey-Taylor relationship for electroluminescence and discharges have been observed from within the light emitting regions. A positive correlation was found to exist between the occurrence of a discharge flare and breakdown of the gap. It is suggested that breakdown was initiated by a trigger discharge at an impurity that had become charged by electron emission from its surface. R E Hurley and P J Dooley, Vacuum, 28 (3), 1978, 147-149. 12 3833. Generation and measurement of subpicosecond electron beam pulses. (USA) The generation and measurement of subpicosecond electron beam pulses by the transverse-longitudinal combination gate system is described. The temporal property of the pulse gate is analysed with the help of the longitudinal emittance diagram. Close agreement has been obtained between the calculated pulse width and the observed one which was measured by the Lissajous's figure method. A beam pulse of 0.2 ps (FWHM) was produced. (Japan) T Hosokawa et al, Rev scient h~strum, 49 (5), 1978, 627-629. 12 3834. Secondary particle collection in ion implantation dose measurement. (USA) The measurement of ion implantation doses in the presence of secondary ions and electrons emitted from the target is discussed. A circuit and electrode geometry for obtaining accurate ion beam current measurements in the presence of both positive and negative secondary particles is presented. D M Jamba, Rev scient lnstrum, 49 (5), 1978, 637-638. 12 3835. Pressure dependence of the rise time of laser-triggered spark gaps. (GB) A laser-triggered spark gap has been built to generate fast pulses which are applied to an electro-optic switch. The LTSG has been designed to give a minimum rise time for a certain gap setting. It has been shown that the parameters, voltage and pressure, which are determined theoretically to give this minimum rise time are in reasonable agreement with the practically measured values. J C Sott and A W Palmer, J Phys E: Sci lnstrum, 11 (5), 1978, 495496. 12 3836. Enrichment of hydrogen isotopes using the low-temperature glow-discharge technique. (USA) Deuterium enrichments are reported for flowing methane/hydrogen mixtures subjected to a glow discharge at low temperatures. Dependence of the enrichment factor on initial D/H ratios, flow rates, system pressure, discharge energies and translational temperature of the reacting gas mixture was studied. In addition to enrichment measurements, details of the estimate of energy requirements for enrichment of deuterium from natural abundance are included. C E Geosling and T J Manuccia, J appl Phys, 49 (5), 1978, 2605-2610. 12 3837. Excitation processes in a Pb--He discharge. (USA) Measurements of the emission from Pb + in the afterglow of a pulsed H e : P b discharge in a large-bore tube and of the intensities of Pb + and Pb emission lines in a small-bore dc discharge tube have been 85