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1206. Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electromagnetic microbalance
Classified Abstracts 1201--1206
Classified A b s t r a c t s Abstracting Editor's Note. The label immediately following the title of each item denotes country of origin of publication, and that at the end of each abstract indicates country of origin of work (where known). General Vacuum Science and Engineering 11.
14.
Production of Low Pressures
14 1203. Pressure dependence of the cataphoretic effect in the rare gases. (U.S.A.) H. J. Oskam, J. Appl. Phys., 34 (3), March 1963, 711.
11 : 21 The use of a helium condensation pump for evacuation of magnetic traps. SeeAbstr. No. 1231.
12.
Kinetic Theory of Gases
14 : 19 1204. A new arrangement for the production of thermal gas flows and the measurement of radiometer forces. (GreatBritain) Using an electromagnetic microbalance, radiometer forces were measured on specimens exposed to a temperature gradient at low pressures. These forces, which were large compared with the sensitivity of the balance, cannot be adequately accounted for by available theories. The forces were measured within a pressure range from 10 -5 to 100 tort as a function of the type of gas, the temperature conditions, the dimensions of the arrangement and the materials and geometry used for the specimens. Equations are given which provide a sufficiently accurate description o f the results for the two limiting cases " mean free path large or small compared with the inside dimensions of the apparatus ". Since the forces are dependent on pressure, they may be used in a pressure gauge which, combined with a buoyancy measurement, covers the range from 10 -e torr to atmospheric pressure. (Germany). (Authors) H. Krupp, E. Robens, G. Sandstede and G. Walter, Vakuum, 13 (8), Aug. 1963, 297-301.
Measurement of Low Pressures
12 : 22 1201. Pressure measurements in small volumes of a few tenths of a cc. in range 20-100 torr. (Germany) The tendency to manufacture gas-filled miniature lamps of very small volumes (a few tenths of a cc) involves increasing difficulties in measuring the initial gas pressure of such lamps ranging from 20 to 100 torr. The authors describe practical means, using either a McLeod gauge or a U tube manometer, depending on lamp volume and initial pressure. The necessary modification to the gauges are described in detail and the relevant formulas are embodied in a monogram facilitating conversion. An accuracy of a few per cent in original pressure is claimed. (Netherlands). (Authors) A. J. Th. Mollet and L. E. Vrenken, Vakuum-Technik, 12 (1), Feb. 1963, 6-12. 12 : 22 1202. The determination of partial pressures with a simple omegatron. (GreatBritain) It is shown that a simple form of omegatron, without guard rings, may be calibrated to determine partial pressures. An omegatron, with a tungsten emitter, was connected for calibration to the vacuum vessel of an ultra-high vacuum system made of stainless steel. The calibrations were made using a magnetic field of 3.5 kG and an r.f. field of 0.4 V/cm. The controls of omegatron head were set at the optimum bias to give maximum sensitivity and resolution for the nitrogen ion N~+. The calibrations were made with commercially available tank gases, viz. HB, D2, He, N2, O~, A, CH,, CO and CO~. Mass spectra for each gas were taken over a range of pressures and from these were determined the fragmentation pattern, relative ion abundance and ion current to pressure relationship. There was evidence that the partial pressure calibration depended on the tubulated speeds of the ion gauge and omegatron head. Mass spectra were then determined in sequence with four Bayard-Alpert-type ion gauges all having similar electrode assemblies but with differing conductances viz. 3.5; 16; 50 1./see and a " n u d e " gauge which had an infinite conductance. The tubulation speed of the omzgatron head was 4 l./sec and from this value the true pressure in the head could be estimated. (Great Britain). (Authors) B. G. W. Allen and B. Lung, Vacuum, 13 (9), Sept. 1963, 359-366.
14 : 22 : 12 Molecular vacuum gauges (utilizing momentum transfer). See Abstr. No. 1237.
Isotope separation by means of a molecular pump. 1232. 15.
14 : 21 See Abstr. No.
Fluid D y n a m i c s
15 : 24 1205. Cleaning vcauum systems by flushing. (U.S.A.) The problem of cleaning the traps in a vacuum system without opening it to air is discussed. A few tests are described in which a non-reactive gas was flushed through a vacuum system from the vacuum-chamber end to the pumps while baking part of the system. The tentative conclusion is that this method is superior to conditioning under vacuum. (U.S.A.). (Author) F. T. Worrell, Vacuum,13 (8), Aug. 1963, 309-311. 16.
G a s e s and S o l i d s
16 : 37 : 29 1206. Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electro. magnetic microbalance. (Great Britain) An apparatus is described by means of which the weight change of solid bodies can be measured at different temperatures in different
12 : 14 : 22 Molecular vacuam gauges (utilizing momentum transfer). See Abstr. No. 1237. 593
Classified A b s t r a c t s Abstracting Editor's Note. The label immediately following the title of each item denotes country of origin of publication, and that at the end of each abstract indicates country of origin of work (where known). General Vacuum Science and Engineering 11.
14.
Production of Low Pressures
14 1203. Pressure dependence of the cataphoretic effect in the rare gases. (U.S.A.) H. J. Oskam, J. Appl. Phys., 34 (3), March 1963, 711.
11 : 21 The use of a helium condensation pump for evacuation of magnetic traps. SeeAbstr. No. 1231.
12.
Kinetic Theory of Gases
14 : 19 1204. A new arrangement for the production of thermal gas flows and the measurement of radiometer forces. (GreatBritain) Using an electromagnetic microbalance, radiometer forces were measured on specimens exposed to a temperature gradient at low pressures. These forces, which were large compared with the sensitivity of the balance, cannot be adequately accounted for by available theories. The forces were measured within a pressure range from 10 -5 to 100 tort as a function of the type of gas, the temperature conditions, the dimensions of the arrangement and the materials and geometry used for the specimens. Equations are given which provide a sufficiently accurate description o f the results for the two limiting cases " mean free path large or small compared with the inside dimensions of the apparatus ". Since the forces are dependent on pressure, they may be used in a pressure gauge which, combined with a buoyancy measurement, covers the range from 10 -e torr to atmospheric pressure. (Germany). (Authors) H. Krupp, E. Robens, G. Sandstede and G. Walter, Vakuum, 13 (8), Aug. 1963, 297-301.
Measurement of Low Pressures
12 : 22 1201. Pressure measurements in small volumes of a few tenths of a cc. in range 20-100 torr. (Germany) The tendency to manufacture gas-filled miniature lamps of very small volumes (a few tenths of a cc) involves increasing difficulties in measuring the initial gas pressure of such lamps ranging from 20 to 100 torr. The authors describe practical means, using either a McLeod gauge or a U tube manometer, depending on lamp volume and initial pressure. The necessary modification to the gauges are described in detail and the relevant formulas are embodied in a monogram facilitating conversion. An accuracy of a few per cent in original pressure is claimed. (Netherlands). (Authors) A. J. Th. Mollet and L. E. Vrenken, Vakuum-Technik, 12 (1), Feb. 1963, 6-12. 12 : 22 1202. The determination of partial pressures with a simple omegatron. (GreatBritain) It is shown that a simple form of omegatron, without guard rings, may be calibrated to determine partial pressures. An omegatron, with a tungsten emitter, was connected for calibration to the vacuum vessel of an ultra-high vacuum system made of stainless steel. The calibrations were made using a magnetic field of 3.5 kG and an r.f. field of 0.4 V/cm. The controls of omegatron head were set at the optimum bias to give maximum sensitivity and resolution for the nitrogen ion N~+. The calibrations were made with commercially available tank gases, viz. HB, D2, He, N2, O~, A, CH,, CO and CO~. Mass spectra for each gas were taken over a range of pressures and from these were determined the fragmentation pattern, relative ion abundance and ion current to pressure relationship. There was evidence that the partial pressure calibration depended on the tubulated speeds of the ion gauge and omegatron head. Mass spectra were then determined in sequence with four Bayard-Alpert-type ion gauges all having similar electrode assemblies but with differing conductances viz. 3.5; 16; 50 1./see and a " n u d e " gauge which had an infinite conductance. The tubulation speed of the omzgatron head was 4 l./sec and from this value the true pressure in the head could be estimated. (Great Britain). (Authors) B. G. W. Allen and B. Lung, Vacuum, 13 (9), Sept. 1963, 359-366.
14 : 22 : 12 Molecular vacuum gauges (utilizing momentum transfer). See Abstr. No. 1237.
Isotope separation by means of a molecular pump. 1232. 15.
14 : 21 See Abstr. No.
Fluid D y n a m i c s
15 : 24 1205. Cleaning vcauum systems by flushing. (U.S.A.) The problem of cleaning the traps in a vacuum system without opening it to air is discussed. A few tests are described in which a non-reactive gas was flushed through a vacuum system from the vacuum-chamber end to the pumps while baking part of the system. The tentative conclusion is that this method is superior to conditioning under vacuum. (U.S.A.). (Author) F. T. Worrell, Vacuum,13 (8), Aug. 1963, 309-311. 16.
G a s e s and S o l i d s
16 : 37 : 29 1206. Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electro. magnetic microbalance. (Great Britain) An apparatus is described by means of which the weight change of solid bodies can be measured at different temperatures in different
12 : 14 : 22 Molecular vacuam gauges (utilizing momentum transfer). See Abstr. No. 1237. 593