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1242. Optically flat diffusion seals made of glass
598
Classified Abstracts 1240--1250
less than the true pressure in the receiver. The authors show how this error can be considerably reduced by some slight modification to the construction of the McLeod gauge. The principal modification is the provision of a longer and narrower rising tube and the fitting of a ground-in ball valve at the trap entrance. The authors investigate such a circuit both theoretically and experimentally for the three gases helium, argon and xenon over the pressure range 10-4-10 -5 torr. By cooling the mercury in the gauge to 10°C, it was found possible to reduce the pumping error to considerablyless than I per cent. (Germany). w . J . s .
Gas desorption of some rubber-type materials. 1207.
24.
22 1240. Influence of a gas discharge on pressure measurements carried out with thermal conductivity gauges. (Germany) Pressure measurements with thermal conductivity gauges may be falsified by several orders of magnitude if atomic hydrogen is present in the gauge tube. Discharges in nitrogen and oxygen did not exhibit this phenomenon. The authors attribute this difference to insufficient dissociation of these gases under the conditions of the discharge or to a rapid neutralization of any atoms by chemical action on the walls of the gauge. (Germany). w. J. s. E. W. Blauth and B. M. U. Scherzer, Vakuum-Technik, 12 (4), May 1963, 110-111. 22 : 56 1241. A transistorized circuit of great voltage stability for heating cathodes of highly evacuated measuring instruments. The author describes a transistorized automatic voltage stabilizer for the range 16.5-22 V. The circuit will pass a maximum current of 5 A and is used for the heating of the cathode of an omegatron. The stabilizer has a control sensitivity of ,~ 560, i.e. variations of entry voltage of =k 14 per cent only affect the exit voltage by =k .25. Similarly, variation of the load current by 1 Amp alters the exit voltage by 6 mV. (Germany). w.J.s. M. Durra, Vakuum-Technik, 12 (4), May 1963, 112-113. 22 : 21 Concerning the ion pumping mechanism in argon and nitrogen. See Abstr. No. 1234. 21 : 12 Pressure measurements in small volumes of a few tenths of a cc. in range 20-100 torr. See Abstr. No. 1201. 22:12 The determination of partial pressures with a simple omegatron. See Abstr. No. 1202.
23.
Plumbing 23 : 16
1242. Optically flat diffusion seals made of glass. (Germany) Diffusion seals are employed in vacuum technique when a seal is required between two high vacuum regions differing slightly in pressure. Up to now this requirement has been met with certain reservations by the use of spherical valves. Their main drawback is restriction of passage combined with difficulty in operation. The authors have developed a type of slide valve consisting of a flat glass plate with a hole which is covered by a second fiat plate acting as a seal. Operation is by means of an external magnet. With cover plate retracted, the passage is fully open (absence of any obstruction). Instructions for making this type of valve are given. It is stated to have functioned satisfactorily in practice.
(Great Britain).
v¢. J. s. J. S. Anderson and H. A. Kamphausen, Vakuum Technik, 12 (5), July 1963, 152-153.
Valves
Cleaning vacuum systems by flushing.
Ch. Meinke and G. Reich, Vakuum-Technik, 12 (3), April 1963, 79-82.
27.
23:16 See Abstr. No.
24 : 15 See Abstr. No. 1205.
Leak Detectors and Leak Detection
27 1243. Improvement in leak detection by the halogen method.
(Germany) Halogen leak detectors in use up to the present will not detect leaks smaller than 1 × 10 -5 torr 1./see. Although this sensitivity suffices for most industrial applications there are many cases where smaller leaks must be guarded against. It appears that the sensitivity and life of halogen detectors can both be very markedly increased by ensuring the presence of an oxidising atmosphere in the detector head either by the actual introduction of oxygen or by arranging an artificial atmospheric leak of suitable amount. In this manner, leaks as small as 5 × 10 7 tort 1./see could be measured, for a pressure rise in the receiver from 1 × 10 -~ torr to 5 × 10 -5 torr. (Germany). w.J.s. E. Meurer, Vakuum-Technik, 12 (2), March 1963, 41-44.
29.
Miscellaneous
29 : 30 1244. Wall-wall interaction between thin magnetic films. (U.S.A.) H. W. Fuller and L. R. Lakin, J. Appl. Phys., 34 (4), Part II, April 1963, 1069. 29 : 30 1245. Negative resistance in thin anodie oxide films. (U.S.A.) S. Paksever and K. Pratinidhi, J. Appl. Phys., 34 (3), March 1963, 711. 29 : 30 1246. Longitudinal permeability in thin permalloy films. (U.S.A.) E. J. Toroh, and R. A. White, J. Appl. Phys., 34 (4), Part II, April 1963, 1064. 29 : 30 1247. Increasing the Kerr magnetic-optic effect in thin films.
(U.S.A.) A. H. Kolk and M. Orlovic, J. Appl. Phys., 34 (4), Part II, April 1963, 1060. 29 : 30 1248. 90 ° magnetization curling in thin films. (U.S.A.) R. M. Hornreich, J. Appl. Phys., 34 (4), Part II, April 1963, 1071. 29 : 30 1249. Magnetic character of very thin permalloy films. (U.S.A.) F. B. Humphorey, J. Appl. Phys., 34 (4), Part II, April 1963, 1067. 29 1250. Angular and magnitude dispersion of the anisotrophy in Magnetic films. (U.S.A.) T. S. Crowther, J. Appl. Phys., 34 (3), March 1963, 580. 29 : 16 : 37 Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electromagnetic mierobalance. See Abstr. No. 1206.
Classified Abstracts 1240--1250
less than the true pressure in the receiver. The authors show how this error can be considerably reduced by some slight modification to the construction of the McLeod gauge. The principal modification is the provision of a longer and narrower rising tube and the fitting of a ground-in ball valve at the trap entrance. The authors investigate such a circuit both theoretically and experimentally for the three gases helium, argon and xenon over the pressure range 10-4-10 -5 torr. By cooling the mercury in the gauge to 10°C, it was found possible to reduce the pumping error to considerablyless than I per cent. (Germany). w . J . s .
Gas desorption of some rubber-type materials. 1207.
24.
22 1240. Influence of a gas discharge on pressure measurements carried out with thermal conductivity gauges. (Germany) Pressure measurements with thermal conductivity gauges may be falsified by several orders of magnitude if atomic hydrogen is present in the gauge tube. Discharges in nitrogen and oxygen did not exhibit this phenomenon. The authors attribute this difference to insufficient dissociation of these gases under the conditions of the discharge or to a rapid neutralization of any atoms by chemical action on the walls of the gauge. (Germany). w. J. s. E. W. Blauth and B. M. U. Scherzer, Vakuum-Technik, 12 (4), May 1963, 110-111. 22 : 56 1241. A transistorized circuit of great voltage stability for heating cathodes of highly evacuated measuring instruments. The author describes a transistorized automatic voltage stabilizer for the range 16.5-22 V. The circuit will pass a maximum current of 5 A and is used for the heating of the cathode of an omegatron. The stabilizer has a control sensitivity of ,~ 560, i.e. variations of entry voltage of =k 14 per cent only affect the exit voltage by =k .25. Similarly, variation of the load current by 1 Amp alters the exit voltage by 6 mV. (Germany). w.J.s. M. Durra, Vakuum-Technik, 12 (4), May 1963, 112-113. 22 : 21 Concerning the ion pumping mechanism in argon and nitrogen. See Abstr. No. 1234. 21 : 12 Pressure measurements in small volumes of a few tenths of a cc. in range 20-100 torr. See Abstr. No. 1201. 22:12 The determination of partial pressures with a simple omegatron. See Abstr. No. 1202.
23.
Plumbing 23 : 16
1242. Optically flat diffusion seals made of glass. (Germany) Diffusion seals are employed in vacuum technique when a seal is required between two high vacuum regions differing slightly in pressure. Up to now this requirement has been met with certain reservations by the use of spherical valves. Their main drawback is restriction of passage combined with difficulty in operation. The authors have developed a type of slide valve consisting of a flat glass plate with a hole which is covered by a second fiat plate acting as a seal. Operation is by means of an external magnet. With cover plate retracted, the passage is fully open (absence of any obstruction). Instructions for making this type of valve are given. It is stated to have functioned satisfactorily in practice.
(Great Britain).
v¢. J. s. J. S. Anderson and H. A. Kamphausen, Vakuum Technik, 12 (5), July 1963, 152-153.
Valves
Cleaning vacuum systems by flushing.
Ch. Meinke and G. Reich, Vakuum-Technik, 12 (3), April 1963, 79-82.
27.
23:16 See Abstr. No.
24 : 15 See Abstr. No. 1205.
Leak Detectors and Leak Detection
27 1243. Improvement in leak detection by the halogen method.
(Germany) Halogen leak detectors in use up to the present will not detect leaks smaller than 1 × 10 -5 torr 1./see. Although this sensitivity suffices for most industrial applications there are many cases where smaller leaks must be guarded against. It appears that the sensitivity and life of halogen detectors can both be very markedly increased by ensuring the presence of an oxidising atmosphere in the detector head either by the actual introduction of oxygen or by arranging an artificial atmospheric leak of suitable amount. In this manner, leaks as small as 5 × 10 7 tort 1./see could be measured, for a pressure rise in the receiver from 1 × 10 -~ torr to 5 × 10 -5 torr. (Germany). w.J.s. E. Meurer, Vakuum-Technik, 12 (2), March 1963, 41-44.
29.
Miscellaneous
29 : 30 1244. Wall-wall interaction between thin magnetic films. (U.S.A.) H. W. Fuller and L. R. Lakin, J. Appl. Phys., 34 (4), Part II, April 1963, 1069. 29 : 30 1245. Negative resistance in thin anodie oxide films. (U.S.A.) S. Paksever and K. Pratinidhi, J. Appl. Phys., 34 (3), March 1963, 711. 29 : 30 1246. Longitudinal permeability in thin permalloy films. (U.S.A.) E. J. Toroh, and R. A. White, J. Appl. Phys., 34 (4), Part II, April 1963, 1064. 29 : 30 1247. Increasing the Kerr magnetic-optic effect in thin films.
(U.S.A.) A. H. Kolk and M. Orlovic, J. Appl. Phys., 34 (4), Part II, April 1963, 1060. 29 : 30 1248. 90 ° magnetization curling in thin films. (U.S.A.) R. M. Hornreich, J. Appl. Phys., 34 (4), Part II, April 1963, 1071. 29 : 30 1249. Magnetic character of very thin permalloy films. (U.S.A.) F. B. Humphorey, J. Appl. Phys., 34 (4), Part II, April 1963, 1067. 29 1250. Angular and magnitude dispersion of the anisotrophy in Magnetic films. (U.S.A.) T. S. Crowther, J. Appl. Phys., 34 (3), March 1963, 580. 29 : 16 : 37 Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electromagnetic mierobalance. See Abstr. No. 1206.