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1587. Calibration of a cold-discharge manometer of the magnetron type for pressures between 10−9 and 10−10 torr
Classified
abstracts
1580-1590
an alloy of high thermionic emission as both cathode and getter. No magnetic field is needed. The cathode-getter is composed of a titanium-niobium alloy containing traces of lanthanum hexaboride; its specific thermionic emission is 200 times that of the conventional type of cathode. The work function is 3.2 eV. The rate of titanium evaporation may be varied over narrow limits by varying the composition of the alloy. G A Koretskii et al, USSR Patent 206796, Appl I Orb Jan 1966, prrh 8riz Feh 1968 (in Rmvian). 21 1580. Type SSNA --OS ultrahigh vacuum sorption pump with nitrogen cooling. (USSR) The design of a sorption pump constructed as a cylinder of internal diameter 100 mm and height 300 mm, is described. Sorbent thickness is 4 mm and the external wall is in contact with liquid nitrogen. Between the evacuated chamber and the sorbent, a LN, trap is inserted. The pumping speed was measured for different height-todiameter ratios and it was found that the speed increases up to the ratio of 3 but above this value it is practically unchanged. The following pumping speeds were obtained: with silicagel No. 6, 85 litres/sec; with NaX zeolite, 300 litres/sec; and with activated charcoal SKT, 385 litres/sec. The pump is evacuated down to IO 6 to 10m3 torr, baked at 400°C by means of an internally built heater and then the LN, trap is filled. After 2 hours pumping a pressure of IO * torr is reached. Ultimate pressures of 8 ’ 10~ 9 torr were obtained by all three sorbents. The LN, capacity is 4 litres and consumption is 60 cm3/hour. The pumping speed is constant in the pressure range IO-’ to 10m2 torr. A V Aref’ev et al, Prihory Tekh Eksper, 13 (3), May Jwre 1968, I49 I53 (in Russian). 21 125 1581. Some characteristics of a zeolite adsorption pump. (Great Britain) Experiments on the pumping performance of a somewhat crude but serviceable design of adsorption pump using zeolite 5 A are described, the refrigerants being liquid nitrogen or solid CO,in alcohol and the pumped gases being air, nitrogen, CO,, He, Ne, and Ar. Construction details of the pump and data on chill time and consumption of refrigerants are indicated. L G Carpenter and R W Bramham, Rep RAE-TR-67150; AD-664524, Jniy 1967, 29 pages (Sci Tech Aermpace Reps, 6 (9), 1346, N68- 18365). ?I 1582. The pumping speed for CO,ofa surface, cooled by liquid nitrogen. (USA) Equipment for the measurement of pumping speed for CO, by a liquid nitrogen cooled surface, at gas temperatures ranging from 136’. to 548’K, is described and the results in the range 6 IO i to 8 10~” torr are discussed. Using these results, it is possible to (Germany) predict the pumping speed of cryosurfaces in vacuum. G Saenger, Rep NASA-TT-F-I 1547, March 1968, I9 paxe,y (Sci Tech Aerospace Reps, 6 (9), 1385, N68-19364). II
1583. Investigation of the discharge characteristics of an intense hotcathode magnetron ion source for getter-ion pumping applications. (Great Britain) Performance characteristics and design of a hot-cathode magnetron getter-ion pump are described. The data on the ion current outputs (I + I p ratio) for 2.5 cm and 4.5 cm cells are given as functions of the anode, repeller, and collector voltages and magnetic fieldstrength. The magnetic fieldstrength at cutoff varies from 40 to about 200 gauss. The optimum l+p ratio equals or exceeds the I/p ratio of single-cell as well as multi-cell Penning-type getter-ion pumps of the same size. A decrease of the I p ratio at low pressures does not occur. The sticking probability for argon is 0.75, which is about ten times the sticking probability obtained in sputter-ion pumps. Argon instability has not been observed, even after prolonged argon pumping at 3.10 j torr. J Visser and Z Th R Salverda, Vucuum, 18 (9). Sept 1968, 501-506. 22. GAUGES 21 1584. Electronic desorption component in the collector current of ionization gauges. (Poland) Pressure measurement was carried out in the range 10 ‘I to IO I’ torr with a modulated Bayard-Alpert gauge and Groszkowski type twoanode Bayard-Alpert gauge which may be transformed into a con696
ventional Bayard-Alpert gauge merely by changing the anode voltages. It was found that the electronic desorption effect cannot be observed in the two-anodes Bayard-Alpert gauge and the desorption corresponds to a collector current of lo-‘* A for a conventional Bayard-Alpert gauge with a tungsten anode, and I.5 IO I8 A for a modulated gauge with a molybdenum anode. The X-ray effect of the gauges, under the same conditions, was determined to be 4 - IO Is A. J Groszkowski, BUN Acadfoion Sci SPr Sci Tech, 16 (4), 1968,341-350 (in English).
‘2 1585. The behaviour of a gauge with reduced electronic desorption effect on changing the anode current. (Poland) A Groszkowski type, two-anode, Bayard-Alpert gauge, which for comparison was transformed into a conventional Bayard-Alpert gauge by changing the anode voltage, was investigated. The gauge was operated at 4 mA and then for I hour the electron current was lowered to 0.04 mA. The measured pressure for a conventional Bayard-Alpert gauge decreased at the start of this period but then slowly increased. For the Groszkowski gauge no long-term slow increase of the measured pressure was observed. This indicates the suppression of the electronic desorption effect in the Groszkowski two-anode gauge. J Groszkowski, Buii Acud Polon Sci, S&r Sci Tech, 16 (4). 1968, 35 I354 (in English) 22 1586. High-speed, dynamic quadrupole mass spectrometer. (USSR) By combining a conventional quadrupole mass spectrometer (200 mm long quadrupoles) and a secondary electron multiplier, a sensitivity of 2 IO !’ torr was obtained for the mass range of I to 150. The scanning speed was I .3 spectra per sec. The design of the hf generator is described in detail. G I Slobodenyuk et al, Priho,:v Trkh Ekk.yper, 13 (3). Ma.v Jnne 1968, I4 I I45 (in Russian). 2’ 1587. Calibration of a cold-discharge manometer of the magnetron type for pressurea between IO- ’ and lo- I0 torr. (USSR) The calibration of a cold-discharge manometer of the magnetron type intended to operate in the pressure range IO Q to IO ‘” torr is described and the conditions required to ensure a stable electric discharge are indicated. The selected operating conditions are: magnetic field 2200 G, anode voltage 3.5 kV. A calibration graph corresponding to these conditions is presented: the graph constitutes a straight line with a slope of 0. I4 A/torr. G T Nikolaev and 0 S Drui, Magtteric Traps, Naukow Dumka, 3, 1968, 209-2 I 3 (in Russitm) 22 1588. All-glass recording membrane manometer. (Great Britain) An all-glass membrane manometer for use at elevated temperatures is described. Pressures in the range IO-760 torr may be recorded with a precision of f I per cent by means of an induction detector connected to a membrane which withstands pressure differences of one atmosphere. A similar device of quartz was constructed for use at temperatures higher than 370°C. (Czechoslovakia) V Chytry and D Lim, J Sci Instrum, Ser 2, 1 (9), 1968, 964-965. 2’ 1589. A mobile calibrator for intermediate range vacuum gauges. (Great Britain) A mobile apparatus is described, which facilitates in situ calibration in the range of pressures below 30 torr. The operating principle is that of incremental transfer of gas from a reservoir into a dump tank by way of transfer volumes. The pressure in the dump tank can be increased in steps of ION:‘, IO 2, IO-’ or I torr. (USA) G D Arney and W F Henderson, J Sci Instrum, Ser 2, 1 (9), 1968, 967-969. 22 1590. Alpha-particle pressure gauge for high altitude constant level balloon flights. (USA) The alpha-particle pressure gauge described gives continuous readings from sea level to pressures less than I millibar with an accuracy in the I-IO millibar range of a few tenths of a millibar. The instrument is a sensitive electrometer measuring the ionization current due to a very weak polonium source of less than 1 microcurie. R L Howard et al, Rev Sci Imfrwn, 39 (7), 1968, 1013--1018.
abstracts
1580-1590
an alloy of high thermionic emission as both cathode and getter. No magnetic field is needed. The cathode-getter is composed of a titanium-niobium alloy containing traces of lanthanum hexaboride; its specific thermionic emission is 200 times that of the conventional type of cathode. The work function is 3.2 eV. The rate of titanium evaporation may be varied over narrow limits by varying the composition of the alloy. G A Koretskii et al, USSR Patent 206796, Appl I Orb Jan 1966, prrh 8riz Feh 1968 (in Rmvian). 21 1580. Type SSNA --OS ultrahigh vacuum sorption pump with nitrogen cooling. (USSR) The design of a sorption pump constructed as a cylinder of internal diameter 100 mm and height 300 mm, is described. Sorbent thickness is 4 mm and the external wall is in contact with liquid nitrogen. Between the evacuated chamber and the sorbent, a LN, trap is inserted. The pumping speed was measured for different height-todiameter ratios and it was found that the speed increases up to the ratio of 3 but above this value it is practically unchanged. The following pumping speeds were obtained: with silicagel No. 6, 85 litres/sec; with NaX zeolite, 300 litres/sec; and with activated charcoal SKT, 385 litres/sec. The pump is evacuated down to IO 6 to 10m3 torr, baked at 400°C by means of an internally built heater and then the LN, trap is filled. After 2 hours pumping a pressure of IO * torr is reached. Ultimate pressures of 8 ’ 10~ 9 torr were obtained by all three sorbents. The LN, capacity is 4 litres and consumption is 60 cm3/hour. The pumping speed is constant in the pressure range IO-’ to 10m2 torr. A V Aref’ev et al, Prihory Tekh Eksper, 13 (3), May Jwre 1968, I49 I53 (in Russian). 21 125 1581. Some characteristics of a zeolite adsorption pump. (Great Britain) Experiments on the pumping performance of a somewhat crude but serviceable design of adsorption pump using zeolite 5 A are described, the refrigerants being liquid nitrogen or solid CO,in alcohol and the pumped gases being air, nitrogen, CO,, He, Ne, and Ar. Construction details of the pump and data on chill time and consumption of refrigerants are indicated. L G Carpenter and R W Bramham, Rep RAE-TR-67150; AD-664524, Jniy 1967, 29 pages (Sci Tech Aermpace Reps, 6 (9), 1346, N68- 18365). ?I 1582. The pumping speed for CO,ofa surface, cooled by liquid nitrogen. (USA) Equipment for the measurement of pumping speed for CO, by a liquid nitrogen cooled surface, at gas temperatures ranging from 136’. to 548’K, is described and the results in the range 6 IO i to 8 10~” torr are discussed. Using these results, it is possible to (Germany) predict the pumping speed of cryosurfaces in vacuum. G Saenger, Rep NASA-TT-F-I 1547, March 1968, I9 paxe,y (Sci Tech Aerospace Reps, 6 (9), 1385, N68-19364). II
1583. Investigation of the discharge characteristics of an intense hotcathode magnetron ion source for getter-ion pumping applications. (Great Britain) Performance characteristics and design of a hot-cathode magnetron getter-ion pump are described. The data on the ion current outputs (I + I p ratio) for 2.5 cm and 4.5 cm cells are given as functions of the anode, repeller, and collector voltages and magnetic fieldstrength. The magnetic fieldstrength at cutoff varies from 40 to about 200 gauss. The optimum l+p ratio equals or exceeds the I/p ratio of single-cell as well as multi-cell Penning-type getter-ion pumps of the same size. A decrease of the I p ratio at low pressures does not occur. The sticking probability for argon is 0.75, which is about ten times the sticking probability obtained in sputter-ion pumps. Argon instability has not been observed, even after prolonged argon pumping at 3.10 j torr. J Visser and Z Th R Salverda, Vucuum, 18 (9). Sept 1968, 501-506. 22. GAUGES 21 1584. Electronic desorption component in the collector current of ionization gauges. (Poland) Pressure measurement was carried out in the range 10 ‘I to IO I’ torr with a modulated Bayard-Alpert gauge and Groszkowski type twoanode Bayard-Alpert gauge which may be transformed into a con696
ventional Bayard-Alpert gauge merely by changing the anode voltages. It was found that the electronic desorption effect cannot be observed in the two-anodes Bayard-Alpert gauge and the desorption corresponds to a collector current of lo-‘* A for a conventional Bayard-Alpert gauge with a tungsten anode, and I.5 IO I8 A for a modulated gauge with a molybdenum anode. The X-ray effect of the gauges, under the same conditions, was determined to be 4 - IO Is A. J Groszkowski, BUN Acadfoion Sci SPr Sci Tech, 16 (4), 1968,341-350 (in English).
‘2 1585. The behaviour of a gauge with reduced electronic desorption effect on changing the anode current. (Poland) A Groszkowski type, two-anode, Bayard-Alpert gauge, which for comparison was transformed into a conventional Bayard-Alpert gauge by changing the anode voltage, was investigated. The gauge was operated at 4 mA and then for I hour the electron current was lowered to 0.04 mA. The measured pressure for a conventional Bayard-Alpert gauge decreased at the start of this period but then slowly increased. For the Groszkowski gauge no long-term slow increase of the measured pressure was observed. This indicates the suppression of the electronic desorption effect in the Groszkowski two-anode gauge. J Groszkowski, Buii Acud Polon Sci, S&r Sci Tech, 16 (4). 1968, 35 I354 (in English) 22 1586. High-speed, dynamic quadrupole mass spectrometer. (USSR) By combining a conventional quadrupole mass spectrometer (200 mm long quadrupoles) and a secondary electron multiplier, a sensitivity of 2 IO !’ torr was obtained for the mass range of I to 150. The scanning speed was I .3 spectra per sec. The design of the hf generator is described in detail. G I Slobodenyuk et al, Priho,:v Trkh Ekk.yper, 13 (3). Ma.v Jnne 1968, I4 I I45 (in Russian). 2’ 1587. Calibration of a cold-discharge manometer of the magnetron type for pressurea between IO- ’ and lo- I0 torr. (USSR) The calibration of a cold-discharge manometer of the magnetron type intended to operate in the pressure range IO Q to IO ‘” torr is described and the conditions required to ensure a stable electric discharge are indicated. The selected operating conditions are: magnetic field 2200 G, anode voltage 3.5 kV. A calibration graph corresponding to these conditions is presented: the graph constitutes a straight line with a slope of 0. I4 A/torr. G T Nikolaev and 0 S Drui, Magtteric Traps, Naukow Dumka, 3, 1968, 209-2 I 3 (in Russitm) 22 1588. All-glass recording membrane manometer. (Great Britain) An all-glass membrane manometer for use at elevated temperatures is described. Pressures in the range IO-760 torr may be recorded with a precision of f I per cent by means of an induction detector connected to a membrane which withstands pressure differences of one atmosphere. A similar device of quartz was constructed for use at temperatures higher than 370°C. (Czechoslovakia) V Chytry and D Lim, J Sci Instrum, Ser 2, 1 (9), 1968, 964-965. 2’ 1589. A mobile calibrator for intermediate range vacuum gauges. (Great Britain) A mobile apparatus is described, which facilitates in situ calibration in the range of pressures below 30 torr. The operating principle is that of incremental transfer of gas from a reservoir into a dump tank by way of transfer volumes. The pressure in the dump tank can be increased in steps of ION:‘, IO 2, IO-’ or I torr. (USA) G D Arney and W F Henderson, J Sci Instrum, Ser 2, 1 (9), 1968, 967-969. 22 1590. Alpha-particle pressure gauge for high altitude constant level balloon flights. (USA) The alpha-particle pressure gauge described gives continuous readings from sea level to pressures less than I millibar with an accuracy in the I-IO millibar range of a few tenths of a millibar. The instrument is a sensitive electrometer measuring the ionization current due to a very weak polonium source of less than 1 microcurie. R L Howard et al, Rev Sci Imfrwn, 39 (7), 1968, 1013--1018.