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481. Angular dependence of critical currents and transition fields of sputter-deposited superconducting films
Classified abstracts
472-483
22 472. Pressure measurement by ionization gauge bead with cold cathode in various conditions of exploitation. (Poland) Technical data of a vacuum gauge intended for pressure measurement in the range of 1 to 10v5 torr in various technological equipments are presented. The results of examinations on operation of the ionization gauge head with cold cathode in high vacuum with frequent admission of air and in various gases are presented. E Adamski and J Felba, Prace Nauk Znst Technol Elektron Polytech Wrocl, No 8, 1973, 59-66 (in Polish). 22 473. Ionization gauge for measurement of pressure in a broad range. (Poland) Possibilities of utilization of ionization gauges for measurement of pressure in the range of 1 to IO-’ torr are considered. Behaviour of an ionization gauge near its upper measuring limit is investigated. Construction and characteristics of gauge heads enabling one to measure pressure in broad intervals are presented. A Halas et al. Prace Nauk Znst Technol Elektron Polvtech Wrocl. No 8, 1973, 67-75 (in Polish). 22 474. Mass spectrometer with trochoidal ion beam. II. (Roumania) A trochoidal mass spectrometer with a high resolving power of 1340 is described. The instrument is used for determination of crosssections of interaction between ions and molecules. D Ioanoviciu et al, Rev Roum Phys, 18 (l), 1973, 75-80. 22 475. Automatic McLeod manometer. (USSR) An automatic McLeod manometer with automatic raising and lowering of mercury, and automatic recording of pressure, is described. The limits of measurement are 5 x 1O-4 and 1 torr. The accuracy of measurements is 2 to 5 ‘A in dependence on pressure. The automatic McLeod gauge is used in industrial equipment for determination of gases in metals using the method of vacuum melting with manometric gas analyzer. G G Glavin et al, Zavod Lab, 38 (8), 1972, 1017 (in Russian). 24. VALVES 24 476. A minimal volume gas sampling valve. (GB) A gas sampling valve operating under vacuum conditions, which enables direct sampling from the bulk of a dynamic or static system and which can be operated by remote control, is described. This particular valve is directly applicable to mass spectrometric analysis and has a sample size of approximately 0.03 ml (- 1 PM). (Canada) T N Bell et al, J Phys E: Scient Znstrum, 6 (12), 1973, 1177-1178. 24 477. Valve assembly for precision and rapid dosage of gases in mass spectrometers. (USSR) Construction of a double valve with fluoroplastic for precision and rapid dosage of gases in mass spectrometers is described. The assembly is used for precision isotopic analysis of oxygen. V E Vetshteyn, Zavod Lab, 38 (8). 1972, 1118-l 119 (in Russian). 24 478. Ultrahigh vacuum gate valve. (USSR) Construction of a simple bakeable ultrahigh vacuum gate valve with metallic gasket is described. The force necessary for closing the valve is applied around a flange connected with the body with the aid of stainless steel elastic elements. V A Marichev, Zavod Lab, 38 (8), 1972, 1017-1018 (in Russian).
25. BAFFLES, TRAPS AND REFRIGERATION
EQUIPMENT
25 479. Liquid-nitrogen forevacuum trap. (USSR) Efficient forevacuum traps cooled with liquid nitrogen are described. The traps prevent vacuum systems from contamination by forevacuum pumps and accelerate pumping out of water vapours from vacuum systems. The traps lower the forepressure from 1O-2 to 10e3 torr. V A Kovalenko et al, Probl Atomic Sci Technol, CON, Kharkov 1971, 62-64 (in Russian).
27. LEAK DETECTORS
AND LEAK DETECTION
27 480. A thermally shielded atmospheric pressure standard leak calibrator. (USA) A method is described for the calibration of capillary and permeation standard leaks. The technique utilizes a capacitance manometer to detect the small pressure change in a defined volume caused by the influx of gas from a standard leak. Corrections are derived for the small volume changes which occur during manometer operation. All measurements are made at atmospheric pressure. A double-walled aluminium and copper cylinder design is utilized to decrease temperature related pressure changes. A limiting drift rate of approximately 4 x 10-j torr/s (Q = 3 x 10vg std cm3/s) in the manometer indication was traced to manometer diaphragm ‘microcreep’. A method to reduce this background to =6 x lo-“’ std cm”/s is described. The unique aspect of the calibrator is its liability to calibrate Freon standard leaks under usage conditions, i.e., using Freon gas with atmospheric pressure on the down-stream side of the leak, down to lo-“’ std cm3/s. Error of measurement ranged from + 10% to 15 %. Calibration results for several leaks are presented. J R Miller, J Vat Sci Technol, 10 (5), 1973, 882-889.
III.
Vacuum
30. EVAPORATION
applications AND SPUTTERING
30 481. Angular dependence of critical currents and transition fields of sputter-deposited superconducting films. (USA) Anisotropies in critical current and transition fields have been measured for sputter-deposited superconducting films. For thicker films, the peak at 0 = 90” in the I,-0 characteristics is strongly marked. As the film thickness decreases, the peak at 0 = 90” tends to reduce, and finally disappears in the film thinner than the critical thickness. Furthermore, the transition fields H, have been found to be anisotropic with respect to the applied fielh direction 0. The marked peak at 0 = 90” in the H,-0 characteristics is found for films thicker than the critical thickness. (Japan) Y Saito and T Anayama, J AppZ Phys, 44 (ll), 1973, 5111-5115. 30 482. Employing purge gas in a screened vacuum deposition arrangement. (Germany) A method for vacuum deposition is described, in which the total screening of substrate and source by deeply cooled bodies is combined with employing purge gas. The cooled screening surfaces form two nearly closed chambers around source and substrate inside the vacuum container. A tubing for purge gas reaches into the substrate chamber near to the substrate surface. The addition arrangements are built into an evaporation equipment, sealed by Viton and evacuated by an oil diffusion pump. Purge gas is introduced while degassing the source, the charge to be evaporated, the substrate and the substrate holder. Until 2 min before the beginning of the evaporation the substrate is in a protecting atmosphere. During evaporation of molybdenum at a rate of 5 A/s pressures between 1 x 1O-7 torr and 5 x lo-* torr are reached. The deposition can already be started 55 min after switching the assembly. J Ruf, Vakkum-Technik, 22 (8), 1973, 239-272 (in German). 30 483. Use of a differential transformer for the measurement of mechanical stresses in thin evaporated films. (Germany) The deflection of thin plates may be used to determine the stress in vacuum deposited films. Two experimental arrangements for the measurement of this deflection are described. Both make use of a linear (voltage) differential transformer to perform the necessary high precision length measurements. The characteristics of the differential transformer used were determined and the dependence of the sensitivity of the final arrangement on different parameters was evaluated. Measurements of stress in evaporated gold films were made with microscope slides or tantalum strips as backing. The results are compared with those from similar experiments as reported in literature. (Belgium) H L Eschbach et al, Vakkum-Technik, 22 (8), 1973, 233-238 (in German). 227
472-483
22 472. Pressure measurement by ionization gauge bead with cold cathode in various conditions of exploitation. (Poland) Technical data of a vacuum gauge intended for pressure measurement in the range of 1 to 10v5 torr in various technological equipments are presented. The results of examinations on operation of the ionization gauge head with cold cathode in high vacuum with frequent admission of air and in various gases are presented. E Adamski and J Felba, Prace Nauk Znst Technol Elektron Polytech Wrocl, No 8, 1973, 59-66 (in Polish). 22 473. Ionization gauge for measurement of pressure in a broad range. (Poland) Possibilities of utilization of ionization gauges for measurement of pressure in the range of 1 to IO-’ torr are considered. Behaviour of an ionization gauge near its upper measuring limit is investigated. Construction and characteristics of gauge heads enabling one to measure pressure in broad intervals are presented. A Halas et al. Prace Nauk Znst Technol Elektron Polvtech Wrocl. No 8, 1973, 67-75 (in Polish). 22 474. Mass spectrometer with trochoidal ion beam. II. (Roumania) A trochoidal mass spectrometer with a high resolving power of 1340 is described. The instrument is used for determination of crosssections of interaction between ions and molecules. D Ioanoviciu et al, Rev Roum Phys, 18 (l), 1973, 75-80. 22 475. Automatic McLeod manometer. (USSR) An automatic McLeod manometer with automatic raising and lowering of mercury, and automatic recording of pressure, is described. The limits of measurement are 5 x 1O-4 and 1 torr. The accuracy of measurements is 2 to 5 ‘A in dependence on pressure. The automatic McLeod gauge is used in industrial equipment for determination of gases in metals using the method of vacuum melting with manometric gas analyzer. G G Glavin et al, Zavod Lab, 38 (8), 1972, 1017 (in Russian). 24. VALVES 24 476. A minimal volume gas sampling valve. (GB) A gas sampling valve operating under vacuum conditions, which enables direct sampling from the bulk of a dynamic or static system and which can be operated by remote control, is described. This particular valve is directly applicable to mass spectrometric analysis and has a sample size of approximately 0.03 ml (- 1 PM). (Canada) T N Bell et al, J Phys E: Scient Znstrum, 6 (12), 1973, 1177-1178. 24 477. Valve assembly for precision and rapid dosage of gases in mass spectrometers. (USSR) Construction of a double valve with fluoroplastic for precision and rapid dosage of gases in mass spectrometers is described. The assembly is used for precision isotopic analysis of oxygen. V E Vetshteyn, Zavod Lab, 38 (8). 1972, 1118-l 119 (in Russian). 24 478. Ultrahigh vacuum gate valve. (USSR) Construction of a simple bakeable ultrahigh vacuum gate valve with metallic gasket is described. The force necessary for closing the valve is applied around a flange connected with the body with the aid of stainless steel elastic elements. V A Marichev, Zavod Lab, 38 (8), 1972, 1017-1018 (in Russian).
25. BAFFLES, TRAPS AND REFRIGERATION
EQUIPMENT
25 479. Liquid-nitrogen forevacuum trap. (USSR) Efficient forevacuum traps cooled with liquid nitrogen are described. The traps prevent vacuum systems from contamination by forevacuum pumps and accelerate pumping out of water vapours from vacuum systems. The traps lower the forepressure from 1O-2 to 10e3 torr. V A Kovalenko et al, Probl Atomic Sci Technol, CON, Kharkov 1971, 62-64 (in Russian).
27. LEAK DETECTORS
AND LEAK DETECTION
27 480. A thermally shielded atmospheric pressure standard leak calibrator. (USA) A method is described for the calibration of capillary and permeation standard leaks. The technique utilizes a capacitance manometer to detect the small pressure change in a defined volume caused by the influx of gas from a standard leak. Corrections are derived for the small volume changes which occur during manometer operation. All measurements are made at atmospheric pressure. A double-walled aluminium and copper cylinder design is utilized to decrease temperature related pressure changes. A limiting drift rate of approximately 4 x 10-j torr/s (Q = 3 x 10vg std cm3/s) in the manometer indication was traced to manometer diaphragm ‘microcreep’. A method to reduce this background to =6 x lo-“’ std cm”/s is described. The unique aspect of the calibrator is its liability to calibrate Freon standard leaks under usage conditions, i.e., using Freon gas with atmospheric pressure on the down-stream side of the leak, down to lo-“’ std cm3/s. Error of measurement ranged from + 10% to 15 %. Calibration results for several leaks are presented. J R Miller, J Vat Sci Technol, 10 (5), 1973, 882-889.
III.
Vacuum
30. EVAPORATION
applications AND SPUTTERING
30 481. Angular dependence of critical currents and transition fields of sputter-deposited superconducting films. (USA) Anisotropies in critical current and transition fields have been measured for sputter-deposited superconducting films. For thicker films, the peak at 0 = 90” in the I,-0 characteristics is strongly marked. As the film thickness decreases, the peak at 0 = 90” tends to reduce, and finally disappears in the film thinner than the critical thickness. Furthermore, the transition fields H, have been found to be anisotropic with respect to the applied fielh direction 0. The marked peak at 0 = 90” in the H,-0 characteristics is found for films thicker than the critical thickness. (Japan) Y Saito and T Anayama, J AppZ Phys, 44 (ll), 1973, 5111-5115. 30 482. Employing purge gas in a screened vacuum deposition arrangement. (Germany) A method for vacuum deposition is described, in which the total screening of substrate and source by deeply cooled bodies is combined with employing purge gas. The cooled screening surfaces form two nearly closed chambers around source and substrate inside the vacuum container. A tubing for purge gas reaches into the substrate chamber near to the substrate surface. The addition arrangements are built into an evaporation equipment, sealed by Viton and evacuated by an oil diffusion pump. Purge gas is introduced while degassing the source, the charge to be evaporated, the substrate and the substrate holder. Until 2 min before the beginning of the evaporation the substrate is in a protecting atmosphere. During evaporation of molybdenum at a rate of 5 A/s pressures between 1 x 1O-7 torr and 5 x lo-* torr are reached. The deposition can already be started 55 min after switching the assembly. J Ruf, Vakkum-Technik, 22 (8), 1973, 239-272 (in German). 30 483. Use of a differential transformer for the measurement of mechanical stresses in thin evaporated films. (Germany) The deflection of thin plates may be used to determine the stress in vacuum deposited films. Two experimental arrangements for the measurement of this deflection are described. Both make use of a linear (voltage) differential transformer to perform the necessary high precision length measurements. The characteristics of the differential transformer used were determined and the dependence of the sensitivity of the final arrangement on different parameters was evaluated. Measurements of stress in evaporated gold films were made with microscope slides or tantalum strips as backing. The results are compared with those from similar experiments as reported in literature. (Belgium) H L Eschbach et al, Vakkum-Technik, 22 (8), 1973, 233-238 (in German). 227