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1661. Vacuum measuring instruments used in the cable industry.
Classified
abstracts
1656-1666
calibrate directly to low gas concentrations without using either a very low gas flow rate or alternatively a very large pumping system as is required by the more usual orifice limited continued flow calibration technique. Experimental results are presented from calibration studies with hydrogen on lOG-13 and ET1 ion gauges, MS10 and PPG mass spectrometers. This work includes studies of gauge pumping and contamination production. A few calibration results are also presented for deuterium and argon. J N Chubb and L Gowland, Vacuum, 16 (8), Aug 1967, 449455. 1656. An investigation into the effect errors on McLeod gauge measurements.
of mercury-vapour (Great Brirain)
22 pumping
Measurements of the mercury-vapour pumping error for argon, kryoton, xenon. CO. CO,, CeF, and C,F, for gas pressures in the range lO-6 to 10m4t&r are reported and-are compared with other available data. The present data are associated with measurement of ionization and attachment cross-sections for electrons in the gases studied and it is shown that for krypton the currently accepted crosssections may be in error by w 15 per cent. The effect of introducing a length of capillary tubing into the line connecting the McLeod gauge and cold trap is discussed briefly. R J Tunnicliffe and J A Rees, Vacuum, 16 (8), Aug 1967, 457-459. 22 1657. Measurement of the variation of molecular impact rate within a spherical calibration vessel. (Great Britain)
When calibrating high vacuum gauges by the dynamic flow method the calibration chamber is continuously exhausted with gas flowing into the vessel at a controlled rate to obtain a given pressure. The gas flow and pumping speed must be sufficient to minimise the effect of gas desorption. An investigation was made of the departure from molecular chaos within a spherical vessel (61 cm in diameter) under the foregoing conditions. Variations in the molecular impact rate were determined around the circumference of the chamber using a movable ionization gauge fitted with a small spherical receiver within which gas molecules with preferred directions were scattered before entering the ionizing region; the instrument is known as a “pressure transducer”. Gas was admitted to the test vessel from a spherical gas reservoir connected to an argon supply. Measurements were made with several types of apertures and tubulations between the reservoir and test vessel. The effect of the geometry of the pumping port and baffle plates on the gas distribution was also studied. The foregoing studies were also made with an ionization gauge having a tubular envelope terminated with an orifice plate for gas admission. The gauge showed an enhanced response to preferred flow when the molecular beam entered its envelope through the orifice at normal incidence because the incident gas passed directly into the most effective ionizing region. In conclusion, the “pressure” variations measured are considered in relation to inaccuracies that could be encountered in gauge calibration systems. L Holland and C Priestland, Vacuum, 16 (8), Aug 1967, 461-467.
LL
1660. Solution of some equations describing the main parameters mass-spectrometer. (USSR)
Measurements of the smallest ion currents are limited not only by the amplifier noise but also by fluctuations of the mass-spectrometer ion current (similar to shot noise in electron tubes). Both factors are taken into account in computing the lowest detectable partial pressure of a mass-spectrometer. Further, a ratio of mass-spectrometer sensitivity to product of its resolution and the whole spectrum scanning rate per second is proposed as the quality factor of a dynamic mass-spectrometer. From manufacturers’ data, the value of this factor for a Soviet omegatron type IPDO-I is 3.6 x IO * torrsec and for quadrupole analyzer AMP 3, 4.8x IO I3 torr.sec. Thus, using the AMP 3 with a scanning speed of 10 spectra per set and with resolution of 100, the lowest detectable partial pressure is 4.8 x lO-ro torr and higher sensitivity may only be obtained when analyzing at a lower scanning speed or with a lower resolution. The highest possible pressure of a residual atmosphere in the mass-spectrometer is also computed. G I Slobodenyuk, Zh Tekh Fiz, 37 (5), May 1967,964-970 (in Russian). 1661. Vacuum (Germany)
measuring
1658. Development of a mass spectrometer system. (USA) A cold cathode ion source of the magnetron type has been developed for use in ultrahigh vacuum residual gas analysis. The purpose was to eliminate the spurious spectra produced by the conventional hot filament ion source and to produce increased sensitivity. Studies were conducted using a commercial quadrupole spectrometer. The commercial unit was not optimally designed for the cold cathode ion source, but allowed both its performanceand potential to beevaluated. Cold cathode quadrupole performance was studied as a function of numerous parameters to determine optimum operating conditions. Resolution of mass peaks 0.7 mu apart was ultimately achieved, with the valley between peaks less than 10 per cent of the height of either adjacent peak. This resolution was identical to that obtained with the commercial hot filament source and appeared limited by the quadrupole itself. Sensitivity exceeded that obtained with the hot filament source. P L Torney and P Blum, Rep NASA-CR-66257, Nov 1966 (National Res Corp, Cambridge,
Massachusetts).
-m
LL
1659. Vacuum measuring systems.
(USA)
Vacuum system components and the instrumentation able for measurement and read-out are described. R W Worrall, Instrumentation, 20 (I), 1967, 22-27. 578
currently avail-
instruments
used
in the cable
22 industry.
Various gauges for measuring pressures down to lO-3 torr and below are described. K H Mirgel, Draht, 17 (5), 1966, 315-322 (in German). 22 1662. Mass spectrometer.
(Great Britain)
Operating on the omegatron principle which may be used for measurement purposes, the spectrometer tube includes a system for producing an electron beam along which ions are formed and a high frequency field created between electrodes. Resonant ions are accelerated in the high frequency field in the presence of a magnetic field so as to impinge on a collector electrode spaced from the electron beam. Non-resonant ions are removed from the ionization space by a negatively charged collector electrode positioned near the beam, after these ions have moved along the beam. (Author) Leybold Holding AC, Brit Putem I ,072,559, Parent Abstr, 7 (28) part D. 14th July 1967, 2.
23. PLUMBING 23 1663. Adhesives, sealants and gaskets-a survey. (USA) As part of a technology utilization program to accelerate the dissemination of technical information developed for space missions, a survey is presented on adhesives, sealants and gaskets developed to operate in the extreme environments encountered in space work. Emphasis is on reliability of materials that can be used in a liquid oxygen environment. The report also describes epoxy ester adhesives, gasket design and measurement of stress in gaskets. R B Perkins and S N Glarum, Rep NASA-SP-5066, 1967 (Southern Res Inst, Birmingham,
LL
of a
Alabama).
23 1664. Apparatus for measuring the shear strength of adhesive joints at high temperatures and methods for constructing the adhesive joints. (Great Britain)
A machine for determining the shear strength of adhesive joints in the temperature range of 20 to 350°C is described. Two methods of constructing suitable adhesive joints are described. R T Humpidge and B J Taylor, J Sri Instrum, 44 (6), June 1967, 457. 23 1665. Ultrahigh vacuum seal.
(USA)
A pressure actuated apparatus for closing an opening in a vacuum wall, consists of a closure disc fitting into the opening with an annular inflatable element around the periphery of the disc. An annular flexible band with an outer surface having a continuous serrated region, is disposed around the periphery of the disc and encircles the inflatable element. A source of high pressure fluid can be coupled to the inflatable element whereby the band is flexed outward, causing the serrated region to bear against the wall of the opening. US Atomic Energy Comm, US Patent 3,331,526, Official Gaz US Patent Ofice, 840 (3), 18th July 1967, 865. 23 1666. Shaft seal with cooling means. (USA) A shaft projecting from the housing of a turbomolecular pump has a
abstracts
1656-1666
calibrate directly to low gas concentrations without using either a very low gas flow rate or alternatively a very large pumping system as is required by the more usual orifice limited continued flow calibration technique. Experimental results are presented from calibration studies with hydrogen on lOG-13 and ET1 ion gauges, MS10 and PPG mass spectrometers. This work includes studies of gauge pumping and contamination production. A few calibration results are also presented for deuterium and argon. J N Chubb and L Gowland, Vacuum, 16 (8), Aug 1967, 449455. 1656. An investigation into the effect errors on McLeod gauge measurements.
of mercury-vapour (Great Brirain)
22 pumping
Measurements of the mercury-vapour pumping error for argon, kryoton, xenon. CO. CO,, CeF, and C,F, for gas pressures in the range lO-6 to 10m4t&r are reported and-are compared with other available data. The present data are associated with measurement of ionization and attachment cross-sections for electrons in the gases studied and it is shown that for krypton the currently accepted crosssections may be in error by w 15 per cent. The effect of introducing a length of capillary tubing into the line connecting the McLeod gauge and cold trap is discussed briefly. R J Tunnicliffe and J A Rees, Vacuum, 16 (8), Aug 1967, 457-459. 22 1657. Measurement of the variation of molecular impact rate within a spherical calibration vessel. (Great Britain)
When calibrating high vacuum gauges by the dynamic flow method the calibration chamber is continuously exhausted with gas flowing into the vessel at a controlled rate to obtain a given pressure. The gas flow and pumping speed must be sufficient to minimise the effect of gas desorption. An investigation was made of the departure from molecular chaos within a spherical vessel (61 cm in diameter) under the foregoing conditions. Variations in the molecular impact rate were determined around the circumference of the chamber using a movable ionization gauge fitted with a small spherical receiver within which gas molecules with preferred directions were scattered before entering the ionizing region; the instrument is known as a “pressure transducer”. Gas was admitted to the test vessel from a spherical gas reservoir connected to an argon supply. Measurements were made with several types of apertures and tubulations between the reservoir and test vessel. The effect of the geometry of the pumping port and baffle plates on the gas distribution was also studied. The foregoing studies were also made with an ionization gauge having a tubular envelope terminated with an orifice plate for gas admission. The gauge showed an enhanced response to preferred flow when the molecular beam entered its envelope through the orifice at normal incidence because the incident gas passed directly into the most effective ionizing region. In conclusion, the “pressure” variations measured are considered in relation to inaccuracies that could be encountered in gauge calibration systems. L Holland and C Priestland, Vacuum, 16 (8), Aug 1967, 461-467.
LL
1660. Solution of some equations describing the main parameters mass-spectrometer. (USSR)
Measurements of the smallest ion currents are limited not only by the amplifier noise but also by fluctuations of the mass-spectrometer ion current (similar to shot noise in electron tubes). Both factors are taken into account in computing the lowest detectable partial pressure of a mass-spectrometer. Further, a ratio of mass-spectrometer sensitivity to product of its resolution and the whole spectrum scanning rate per second is proposed as the quality factor of a dynamic mass-spectrometer. From manufacturers’ data, the value of this factor for a Soviet omegatron type IPDO-I is 3.6 x IO * torrsec and for quadrupole analyzer AMP 3, 4.8x IO I3 torr.sec. Thus, using the AMP 3 with a scanning speed of 10 spectra per set and with resolution of 100, the lowest detectable partial pressure is 4.8 x lO-ro torr and higher sensitivity may only be obtained when analyzing at a lower scanning speed or with a lower resolution. The highest possible pressure of a residual atmosphere in the mass-spectrometer is also computed. G I Slobodenyuk, Zh Tekh Fiz, 37 (5), May 1967,964-970 (in Russian). 1661. Vacuum (Germany)
measuring
1658. Development of a mass spectrometer system. (USA) A cold cathode ion source of the magnetron type has been developed for use in ultrahigh vacuum residual gas analysis. The purpose was to eliminate the spurious spectra produced by the conventional hot filament ion source and to produce increased sensitivity. Studies were conducted using a commercial quadrupole spectrometer. The commercial unit was not optimally designed for the cold cathode ion source, but allowed both its performanceand potential to beevaluated. Cold cathode quadrupole performance was studied as a function of numerous parameters to determine optimum operating conditions. Resolution of mass peaks 0.7 mu apart was ultimately achieved, with the valley between peaks less than 10 per cent of the height of either adjacent peak. This resolution was identical to that obtained with the commercial hot filament source and appeared limited by the quadrupole itself. Sensitivity exceeded that obtained with the hot filament source. P L Torney and P Blum, Rep NASA-CR-66257, Nov 1966 (National Res Corp, Cambridge,
Massachusetts).
-m
LL
1659. Vacuum measuring systems.
(USA)
Vacuum system components and the instrumentation able for measurement and read-out are described. R W Worrall, Instrumentation, 20 (I), 1967, 22-27. 578
currently avail-
instruments
used
in the cable
22 industry.
Various gauges for measuring pressures down to lO-3 torr and below are described. K H Mirgel, Draht, 17 (5), 1966, 315-322 (in German). 22 1662. Mass spectrometer.
(Great Britain)
Operating on the omegatron principle which may be used for measurement purposes, the spectrometer tube includes a system for producing an electron beam along which ions are formed and a high frequency field created between electrodes. Resonant ions are accelerated in the high frequency field in the presence of a magnetic field so as to impinge on a collector electrode spaced from the electron beam. Non-resonant ions are removed from the ionization space by a negatively charged collector electrode positioned near the beam, after these ions have moved along the beam. (Author) Leybold Holding AC, Brit Putem I ,072,559, Parent Abstr, 7 (28) part D. 14th July 1967, 2.
23. PLUMBING 23 1663. Adhesives, sealants and gaskets-a survey. (USA) As part of a technology utilization program to accelerate the dissemination of technical information developed for space missions, a survey is presented on adhesives, sealants and gaskets developed to operate in the extreme environments encountered in space work. Emphasis is on reliability of materials that can be used in a liquid oxygen environment. The report also describes epoxy ester adhesives, gasket design and measurement of stress in gaskets. R B Perkins and S N Glarum, Rep NASA-SP-5066, 1967 (Southern Res Inst, Birmingham,
LL
of a
Alabama).
23 1664. Apparatus for measuring the shear strength of adhesive joints at high temperatures and methods for constructing the adhesive joints. (Great Britain)
A machine for determining the shear strength of adhesive joints in the temperature range of 20 to 350°C is described. Two methods of constructing suitable adhesive joints are described. R T Humpidge and B J Taylor, J Sri Instrum, 44 (6), June 1967, 457. 23 1665. Ultrahigh vacuum seal.
(USA)
A pressure actuated apparatus for closing an opening in a vacuum wall, consists of a closure disc fitting into the opening with an annular inflatable element around the periphery of the disc. An annular flexible band with an outer surface having a continuous serrated region, is disposed around the periphery of the disc and encircles the inflatable element. A source of high pressure fluid can be coupled to the inflatable element whereby the band is flexed outward, causing the serrated region to bear against the wall of the opening. US Atomic Energy Comm, US Patent 3,331,526, Official Gaz US Patent Ofice, 840 (3), 18th July 1967, 865. 23 1666. Shaft seal with cooling means. (USA) A shaft projecting from the housing of a turbomolecular pump has a