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12. Measurement of low pressures
Classified Abstracts 1166--1172
Classified Abstracts Abstracting Editor's Note. The label immediately following the title of each item denotes country oJ origin o.[ publication, and that at the end of each abstract indicates country of origin of work (where known).
General Vacuum Science and Engineering 11.
Production of Low Pressures
11 : 19 1166. Pseudo window for use in production of soft ultra-high vacuum with vacuum ultra-violet and soft X-ray monochromators.
(u.s.A.) N. N. Axelrod, Rev. Sei. lnstrum., 35 (7), July 1964, 918-919. 11 1167. Modern methods of obtaining ultra-high vacuum. (U.S.A.) A comprehensive article discussing methods such as sorption which do not employ a working fluid. In order to obtain low pressures, the corresponding devices, including turbo-molecular pumps, are fully described and their pumping speed compared. Nearly 100 references are given. (U.S.S.R.) E. M. Reikhrudel and G. B. Smirnitskaya, Zh. Tekh. Fiz., 33 (12), Dec. 1963, 1405-1429 ; translated in Soviet Phys. Tech. Physics, 8 (12), June 1964, 1045-1062. 12.
sion of a pressure o f p units to the new scale in dB is accomplished by the formula dB = 101ogz0p + C Values of C for various p scales is given below p C Bar O torr --28.75 atmospheres + 0.0572 Advantages claimed for the dB system : (1) It furnishes a unified scale encompassing the whole range from smallest to greatest values. (2) It centres round a convenient and absolute reference value of approximately one standard atmosphere. (3) The numeric in its units place the accuracy attributable to the majority of pressure designations which lie outside the simple barometric column or the McLeod gauge. G. C. Baldwin and L. Tonks, Nature, 203 (4945), 8 Aug. 1964, 633-634. 12:22 1170. On the calibration of a Pirani gauge. (Japan) The calibration system consists of a large volume tank (~231), a variable leak and a burette for measuring small flow rates of various gases at low pressure. The calibration was carried out with H, N2, He and A over the pressure range 0-80~Hg and flow rates between 0.5 and 5~Hg l./sec. Calibration with large flow rates showed deviations from a straight line by 1-4 per cent at the lowest pressures, the effect being most marked in the case of N~ and least for H~. Over the experimental range, the filament temperature of the gauge varied from 80°C to 200°C with an average power consumption of 4 W. (Japan)
Measurement of Low Pressures
12:22 1168. The accurate measurement of degree of vacuum in scientific research. (U.S.S.R.) An exact knowledge of the ambient gas pressure in which physical phenomena take place is becoming more and more important. Thus accurate gauges are required when investigating phenomena in the upper atmosphere or more generally in space. This of course includes ground simulators. In addition gauges are required in industry and finally we have the vast field of electronics much of which requires the accurate maintenance of a specified low pressure. The development of so called " noiseless " valves for long range space communication is quoted as an instance. The author divides the pressure range between normal atmospheric and ultra-high vacuum into four ranges as shown in the following table which also indicates the percentage accuracy to be expected in each case with available pressure gauges of Russian manufacture.
T. Fujino, J. Vac. Soc., 7 (7), 1964, 247-252.
(In Japanese) 12 : 61
1171. Units in vacuum measurements.
(Great Britain)
Under ultra-high vacuum conditions, the term " pressure " becomes ambiguous and the author suggests that the logarithm of the number of molecules per cubic metre should be used as a new unit for calibrating ionization gauges. The zero of this scale (one molecule per m 3) corresponds to 2.83 × 10_23 torr.
Pressure Range in tort Percentage gauge error 750-10 2 0.1-0.5 10-2--10 _6 1--5 10-6--10 -8 5--10 10 s-10-t2 10-50 Ten gauges of Soviet manufacture are listed together with their respective pressure ranges. The only gauge recording down to 10 -12 torr is the inverse magnetron gauge VIM-1. Two gauges record down to 10-l° torr, the omegatron IPBO-1 and the ionization gauge Vl-12. A calibration circuit covering the range 20 torr to 10 -1° torr is described. (U.S.S.R.) M. A. Guilavev and A. V. Erinkhin, Measurement Techniques, 6, 1964, 17-20. (In Russian)
(Great Britain) F. T. Worrell, Nature, 199 (4892), 3 Aug. 1963, 476-477. 12 : 22 1172. Allowance for the evacuating effect of mercury vapour in calibrating electrical discharge manometers by means of a mercury compression manometer. (U.S.A.) A. V. Eryukhin, Izmerit Teknika, 12, Dec. 1963, 20 ; translated in Measurement Tech., 12, June 1964, 1006-1007.
12 : 61 1169. Logarithmic pressure scale. A scale is purposed in which the logarithm of the absolute pressure in bars (106 dynes/cm 2) is used as a measure. Conver-
15.
Fluid Dynamics 15
Shock waves in low density plasma.
493
See Abstr. No. 1188.
Classified Abstracts Abstracting Editor's Note. The label immediately following the title of each item denotes country oJ origin o.[ publication, and that at the end of each abstract indicates country of origin of work (where known).
General Vacuum Science and Engineering 11.
Production of Low Pressures
11 : 19 1166. Pseudo window for use in production of soft ultra-high vacuum with vacuum ultra-violet and soft X-ray monochromators.
(u.s.A.) N. N. Axelrod, Rev. Sei. lnstrum., 35 (7), July 1964, 918-919. 11 1167. Modern methods of obtaining ultra-high vacuum. (U.S.A.) A comprehensive article discussing methods such as sorption which do not employ a working fluid. In order to obtain low pressures, the corresponding devices, including turbo-molecular pumps, are fully described and their pumping speed compared. Nearly 100 references are given. (U.S.S.R.) E. M. Reikhrudel and G. B. Smirnitskaya, Zh. Tekh. Fiz., 33 (12), Dec. 1963, 1405-1429 ; translated in Soviet Phys. Tech. Physics, 8 (12), June 1964, 1045-1062. 12.
sion of a pressure o f p units to the new scale in dB is accomplished by the formula dB = 101ogz0p + C Values of C for various p scales is given below p C Bar O torr --28.75 atmospheres + 0.0572 Advantages claimed for the dB system : (1) It furnishes a unified scale encompassing the whole range from smallest to greatest values. (2) It centres round a convenient and absolute reference value of approximately one standard atmosphere. (3) The numeric in its units place the accuracy attributable to the majority of pressure designations which lie outside the simple barometric column or the McLeod gauge. G. C. Baldwin and L. Tonks, Nature, 203 (4945), 8 Aug. 1964, 633-634. 12:22 1170. On the calibration of a Pirani gauge. (Japan) The calibration system consists of a large volume tank (~231), a variable leak and a burette for measuring small flow rates of various gases at low pressure. The calibration was carried out with H, N2, He and A over the pressure range 0-80~Hg and flow rates between 0.5 and 5~Hg l./sec. Calibration with large flow rates showed deviations from a straight line by 1-4 per cent at the lowest pressures, the effect being most marked in the case of N~ and least for H~. Over the experimental range, the filament temperature of the gauge varied from 80°C to 200°C with an average power consumption of 4 W. (Japan)
Measurement of Low Pressures
12:22 1168. The accurate measurement of degree of vacuum in scientific research. (U.S.S.R.) An exact knowledge of the ambient gas pressure in which physical phenomena take place is becoming more and more important. Thus accurate gauges are required when investigating phenomena in the upper atmosphere or more generally in space. This of course includes ground simulators. In addition gauges are required in industry and finally we have the vast field of electronics much of which requires the accurate maintenance of a specified low pressure. The development of so called " noiseless " valves for long range space communication is quoted as an instance. The author divides the pressure range between normal atmospheric and ultra-high vacuum into four ranges as shown in the following table which also indicates the percentage accuracy to be expected in each case with available pressure gauges of Russian manufacture.
T. Fujino, J. Vac. Soc., 7 (7), 1964, 247-252.
(In Japanese) 12 : 61
1171. Units in vacuum measurements.
(Great Britain)
Under ultra-high vacuum conditions, the term " pressure " becomes ambiguous and the author suggests that the logarithm of the number of molecules per cubic metre should be used as a new unit for calibrating ionization gauges. The zero of this scale (one molecule per m 3) corresponds to 2.83 × 10_23 torr.
Pressure Range in tort Percentage gauge error 750-10 2 0.1-0.5 10-2--10 _6 1--5 10-6--10 -8 5--10 10 s-10-t2 10-50 Ten gauges of Soviet manufacture are listed together with their respective pressure ranges. The only gauge recording down to 10 -12 torr is the inverse magnetron gauge VIM-1. Two gauges record down to 10-l° torr, the omegatron IPBO-1 and the ionization gauge Vl-12. A calibration circuit covering the range 20 torr to 10 -1° torr is described. (U.S.S.R.) M. A. Guilavev and A. V. Erinkhin, Measurement Techniques, 6, 1964, 17-20. (In Russian)
(Great Britain) F. T. Worrell, Nature, 199 (4892), 3 Aug. 1963, 476-477. 12 : 22 1172. Allowance for the evacuating effect of mercury vapour in calibrating electrical discharge manometers by means of a mercury compression manometer. (U.S.A.) A. V. Eryukhin, Izmerit Teknika, 12, Dec. 1963, 20 ; translated in Measurement Tech., 12, June 1964, 1006-1007.
12 : 61 1169. Logarithmic pressure scale. A scale is purposed in which the logarithm of the absolute pressure in bars (106 dynes/cm 2) is used as a measure. Conver-
15.
Fluid Dynamics 15
Shock waves in low density plasma.
493
See Abstr. No. 1188.