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1100. Theory of Knudsen's absolute manometer
Classified abstracts 1099-1112 accuracy of 5 per cent. The principles and operation of the apparatus are described. K Falor, lnstrum Control Syst, 39, 1966, 93-97. 22 1099. Vacuum gauge calibration. (USA) A 10-760 torr direct comparison of a vacuum gauge with a barometric mercury manometer having an accuracy of 4-0.01 tort is accepted as standard. The equipment required includes the manometer, a small mechanical pump, a header with a few valves, and a supply of dry inert gas for back filling. S Giles, Test Eng Mgt, 15, 1966. 30-31. 22 I100. Theory of Knudsen's absolute manometer. (Germany) The theory of the absolute manometer of Knudsen has been developed rigorously according to the revised theory of thermal transpiration which has been established recently by Wu. The present theory has been compared with Knudsen's and Smoluchowski's theories for certain boundary conditions. This paper presents a generalised theory of the absolute manometer for any temperature ratio and arbitrary accommodation coefficients on the boundaries. Y Wu+ Ann Phys, 18, 1966, 321-330. 22 I101. Mechanism of current formation in plane vacuum chambers. (USSR) The theory underlying current formation in a plane vacuum chamber of the type used for measuring large dose rates of x-rays or y-radiation is discussed. Electrodes differing either in material or dimensions emit different numbers of electrons when subjected to the action of strong x-ray beams. When two such electrodes are placed in close proximity in a vacuum tube, a difference current is set up between them; this current serves as a measure of the dose rate of the x-radiation. A N Ivanov, lzv Leningradsk Elektrotekh Inst (Lenina), No 61, 1966, 43 (in Russian). 22 1102. A control system for a molecular vacuum gauge. (Great Britain) An electronic control unit for use with a vibrating vane molecular vacuum gauge is described. The requirements of gauge control are discussed, the gauge sensing and driving arrangements being in the form of a differential capacitor. The method of sensing used is that of measuring change in capacitance as the vane vibrates by means of a frequency modulation system providing a voltage which is a function of vibration amplitude. R G Christian, Electron Eng, 38, 1966, 772-777.
23. PLUMBING 23 ! 103. Easily fabricated high vacuum wire seals. (USA) Aluminium wire seals are finding applications in a number of high vacuum system joints. The AI wire seal described in this article satisfies the following requirements: ability to be readily formed to any desired outline shape without restriction as to size; reliable performance, economy and ease of fabrication. T C Tang and D L Collins, Res/Develop, Mar 1967, 52-54. 23 1104. Bakeahle infra red window for ultrahigh vacuum service. (USA) This note describes a bakeable vacuum seal between a sterling silver flange and a T-12 IR window, with silver chloride as the sealant. This seal is effective from room temperature to 250°C and can probably be used to 400°C. The low vapour pressure of AgCI makes it suitable for ultrahigh vacuum systems. M M Eisenstadtt, Rev Sci Instrum, 38, 1967, 134-135. 23 1105. A simple method for preparation of AgCI sheets for bakeable vacuum-tight seals. (Great Britain) AgC1 sheets for bakeable vacuum-tight seals are produced by rolling out ingots of AgC1. C F van Huysteen, J Sci Instrum, 44, 1967, 172. 23 1106. A bakeable quartz-metal sealed window. (Great Britain) A method is described for joining quartz discs to " K o v a r " tubes under vacuum using inductive heating. The leakages obtained are
less than 1 ntorr/sec, after tests, and the joints are able to operate at a temperature of 400°C and 20 atmospheres or vacuum. K Klein and L Verheydea, J Sci lnstrum, 44, 1967, 174-176. 23 1107. Glass-to-metal seal. (Great Britain) The metal extends through a body of glass where the coefficient of thermal expansion of the glass and that of the metal are not matched, as in conductive rods to the filament of an electric lamp. The metal rod has a part covered by glass of a lower coefficient of expansion than the rod. Its shape restricts relative movement between the glass and rod along its length. A region of non-circular crosssection restricts relative rotational movement between the glass and the rod. (Author) British Sealed Beams Ltd, Brit Patent 1,058,194, Patent Abstr, 7 (9) part C, 3rd March 1967, 7. 23 1108. Metal-to-glass joint. (Great Britain) A method of securing a metal connection in a glass member, the coefficient of thermal expansion of the metal being greater than that of the glass, consists in circumferentially grooving the metal member, passing it through an opening in the glass member and fusing or softening the latter in the vicinity of the groove, so that the glass enters the latter, then allowing the assembly to cool. The shape of the groove side walls, if produced towards the axis of the metal member, would meet the axis without meeting each other. The method is suitable for joining both soda-lime and borosilicate glasses to connections made of alloy or stainless steels, the sides of the groove in the metal part preferentially being either undercut or parallel. (Author) G S Zejma, Brit Patent 1,058,848, Patent Abstr, 7 (10), part 6, lOth March 1967, 2.
24. VALVES 24 1109. Pressure control valves. (USA) The factors affecting the selection, the various types and the selection procedure are all discussed with respect to pressure control valves. J J Pippenger, Machine Design, 38, 1966, 38-40. 24 1110. Plate valve for protecting part of a vacuum chamber from incident vapours. (USSR) A new form of plate valve for completely protecting part of a vacuum chamber from incident vapours is described. The plates are interconnected by projections forming an integral part of each plate and running in circular grooves in the adjacent plates. The whole set of plates is built on a common axis in the form of a fan, one of them being rigidly attached to the axis, which is geared to a drive rod. Incorporation of this valve is especially valuable in improving the quality of thin vacuum-evaporated condensates. A A Abukov, USSR Patent No 182,456, Appl 30th Nov 1964, pubM 27th July 1966. 24 1111. Mass spectrometer gas feed. (Great Britain) To introduce gas samples into a mass spectrometer operating at low pressure, the gas is fed through a capillary into an intermediate chamber connected to a vacuum pump and also to the low pressure chamber of the spectrometer by a second capillary. Pressure in the spectrometer is lower than that in the intermediate chamber and the rate of gas introduction may be regulated by control of the sizes of the capillary tubes. Soe Nat des Petroles d'Aquitaiue, Brit Patent 1,059,755, Patent Abstr, 7 (ll),part D, 17th March 1967, 6. 26. AUTOMATIC MENT
PROTECTIVE
AND
CONTROL
EQUIP-
26 1112. Device for converting helium dewar into continuous temperature cryostat. (USA) A very inexpensive device is described which permits the ready conversion of a conventional liquid helium dewar to a cryostat capable of maintaining constant temperatures between 4.2 and 77°K with very modest heat inputs. B Welber and E E Tynan, Rev Sci Instrum, 38, 1967, 137-138.
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23. PLUMBING 23 ! 103. Easily fabricated high vacuum wire seals. (USA) Aluminium wire seals are finding applications in a number of high vacuum system joints. The AI wire seal described in this article satisfies the following requirements: ability to be readily formed to any desired outline shape without restriction as to size; reliable performance, economy and ease of fabrication. T C Tang and D L Collins, Res/Develop, Mar 1967, 52-54. 23 1104. Bakeahle infra red window for ultrahigh vacuum service. (USA) This note describes a bakeable vacuum seal between a sterling silver flange and a T-12 IR window, with silver chloride as the sealant. This seal is effective from room temperature to 250°C and can probably be used to 400°C. The low vapour pressure of AgCI makes it suitable for ultrahigh vacuum systems. M M Eisenstadtt, Rev Sci Instrum, 38, 1967, 134-135. 23 1105. A simple method for preparation of AgCI sheets for bakeable vacuum-tight seals. (Great Britain) AgC1 sheets for bakeable vacuum-tight seals are produced by rolling out ingots of AgC1. C F van Huysteen, J Sci Instrum, 44, 1967, 172. 23 1106. A bakeable quartz-metal sealed window. (Great Britain) A method is described for joining quartz discs to " K o v a r " tubes under vacuum using inductive heating. The leakages obtained are
less than 1 ntorr/sec, after tests, and the joints are able to operate at a temperature of 400°C and 20 atmospheres or vacuum. K Klein and L Verheydea, J Sci lnstrum, 44, 1967, 174-176. 23 1107. Glass-to-metal seal. (Great Britain) The metal extends through a body of glass where the coefficient of thermal expansion of the glass and that of the metal are not matched, as in conductive rods to the filament of an electric lamp. The metal rod has a part covered by glass of a lower coefficient of expansion than the rod. Its shape restricts relative movement between the glass and rod along its length. A region of non-circular crosssection restricts relative rotational movement between the glass and the rod. (Author) British Sealed Beams Ltd, Brit Patent 1,058,194, Patent Abstr, 7 (9) part C, 3rd March 1967, 7. 23 1108. Metal-to-glass joint. (Great Britain) A method of securing a metal connection in a glass member, the coefficient of thermal expansion of the metal being greater than that of the glass, consists in circumferentially grooving the metal member, passing it through an opening in the glass member and fusing or softening the latter in the vicinity of the groove, so that the glass enters the latter, then allowing the assembly to cool. The shape of the groove side walls, if produced towards the axis of the metal member, would meet the axis without meeting each other. The method is suitable for joining both soda-lime and borosilicate glasses to connections made of alloy or stainless steels, the sides of the groove in the metal part preferentially being either undercut or parallel. (Author) G S Zejma, Brit Patent 1,058,848, Patent Abstr, 7 (10), part 6, lOth March 1967, 2.
24. VALVES 24 1109. Pressure control valves. (USA) The factors affecting the selection, the various types and the selection procedure are all discussed with respect to pressure control valves. J J Pippenger, Machine Design, 38, 1966, 38-40. 24 1110. Plate valve for protecting part of a vacuum chamber from incident vapours. (USSR) A new form of plate valve for completely protecting part of a vacuum chamber from incident vapours is described. The plates are interconnected by projections forming an integral part of each plate and running in circular grooves in the adjacent plates. The whole set of plates is built on a common axis in the form of a fan, one of them being rigidly attached to the axis, which is geared to a drive rod. Incorporation of this valve is especially valuable in improving the quality of thin vacuum-evaporated condensates. A A Abukov, USSR Patent No 182,456, Appl 30th Nov 1964, pubM 27th July 1966. 24 1111. Mass spectrometer gas feed. (Great Britain) To introduce gas samples into a mass spectrometer operating at low pressure, the gas is fed through a capillary into an intermediate chamber connected to a vacuum pump and also to the low pressure chamber of the spectrometer by a second capillary. Pressure in the spectrometer is lower than that in the intermediate chamber and the rate of gas introduction may be regulated by control of the sizes of the capillary tubes. Soe Nat des Petroles d'Aquitaiue, Brit Patent 1,059,755, Patent Abstr, 7 (ll),part D, 17th March 1967, 6. 26. AUTOMATIC MENT
PROTECTIVE
AND
CONTROL
EQUIP-
26 1112. Device for converting helium dewar into continuous temperature cryostat. (USA) A very inexpensive device is described which permits the ready conversion of a conventional liquid helium dewar to a cryostat capable of maintaining constant temperatures between 4.2 and 77°K with very modest heat inputs. B Welber and E E Tynan, Rev Sci Instrum, 38, 1967, 137-138.
363