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Machined carbon products
VACUUM Classified Abstracts
II 2
Vacuum
Apparatus
20 -
PUMPS
and Auxiliaries
-
Abstract 1\o. and Keferences
--- II
20
A High-Speed Hot Baffle for Oil Diffusion Pump Systems
126/H
United States. Details are given of a device which is intended to stop the migration of oil vapour from the pump to the vacuum system more effectively than baffles of the conventional design. It consists of an electrical heater element inserted into the manifold near the mouth of the pump and kept at a temperature of 650°C. Oil vapour striking the hot surface is immediately decomposed into permanent gases, such as hydrogen, and non-volatile carbon. The new device remains active over the whole of its surface whereas the baffles ordinarily used tend to become saturated in operation. The pressure of the decomposition products of the oil vapour striking the hot surface totals less than 10-9mm. Hg.
Note by R. L. Loneini
Sommaire : L’on donne des details d’une chicane chauffee jusqu ‘a 650°C et qui decompose les vapeurs d’huile diffusant de la pompe a huile dans le systeme & vide.
127/R
Laboratory Apparatus for the Distillation of Oils for Diffusion Pumps
0
Pump Oils of a certain composition have been distilled under vacuum in a laboratory-size column. France. Pumps running on oil treated in the manner described produced a vacuum of the order of 1 x 10-Bmm. Hg. Prior to the introduction of this process the lowest pressure obtainable was 7 x 10-6mm. Hg. Details of the method and the equipment required are given. Sommaive : Description d’un procede de distillation de pompage en partant d’huiles convenables.
de laboratoire
recommande
pour la preparation
Article by ~tiAZ$ll& Le Vide I, Ju’y$;t. 1951
de fluides
Silicone Oil Vapour and Secondary Electron Emission
128/E
United Kingdom. Secondary electron emission in a system evacuated by silicone oil diffusion pumps has been studied. Determining the ‘ sticking ’ potential of a fluorescent powder the initial values obtained were of the order expected but under electron bombardment the secondary emission began to fall off within 30 minutes and the sticking potential dropped from 30 to 1.5 kV. In another series of experiments various surfaces in an ‘ orbital beam ’ electrode system have been investigated. One of the materials examined was a mixture of magnesium and barium oxide. The source of primaribs was a tungsten filament. Heating the secondary cathode to 1,OOO”Cand allowing it to cool the secondary emission coefficient dropped from an initial value of 5 to 1.5. A dark deposit could be noticed on the secondary cathode and staining of a similar kind on the anode The nature of the deposit was not determined. and glass bulb of the ionisation gauge. No such effects could be found on thermionic emitters. As a result of these experiments it is believed that silicone settling on the bombarded electrode may be decomposed, but thermionic emitters are too hot to permit the formation of a silicone film. Sommaire d’electrons
Letter by A. Lempicki & A. B. McFarlane Nature 167, 195.1951 81#814
: Les effets d’huile silicone utilisee comme fluide dans des pompes & diffusion sur l’emission secondaire dans les systemes CvacuCs sont Ctudies.
129/11
Vacuum Refrigeration
0
See Abstract
No.
: 169/111 130/R
Machined Carbon Products See Abstract
No.
: 149/11
21 -
GAUGES
-
21
131/R
Vacuum Gauge Using Alpha-Rays This is a short note describing the design and performance of a gauge similar in construction to the France. alphatron gauge. Polonium is used as the source of alpha-particles. The gauge can be employed for pressure readings in the range of 10-l to 10amm. Hg. It is specially recommended for the measurement of the pressure of corrosive gases, for instance halogens and is, therefore, particularly suitable for use in connection with the production of Geiger counters. Finally, it could serve as an indicator of the partial pressure exercised by a component gas in a gas mixture, e.g. neon in a neon-argon mixture. Sommaire
Note br G. Gimen& & J. Labeyrie J. Phys. Radium 12, Oct. 1951 64A85A
: Etude de la construction et des performances d’une jauge 8. ionisation & particle alpha.
-I October, 7951
Vacuum
321
II 2
Vacuum
Apparatus
20 -
PUMPS
and Auxiliaries
-
Abstract 1\o. and Keferences
--- II
20
A High-Speed Hot Baffle for Oil Diffusion Pump Systems
126/H
United States. Details are given of a device which is intended to stop the migration of oil vapour from the pump to the vacuum system more effectively than baffles of the conventional design. It consists of an electrical heater element inserted into the manifold near the mouth of the pump and kept at a temperature of 650°C. Oil vapour striking the hot surface is immediately decomposed into permanent gases, such as hydrogen, and non-volatile carbon. The new device remains active over the whole of its surface whereas the baffles ordinarily used tend to become saturated in operation. The pressure of the decomposition products of the oil vapour striking the hot surface totals less than 10-9mm. Hg.
Note by R. L. Loneini
Sommaire : L’on donne des details d’une chicane chauffee jusqu ‘a 650°C et qui decompose les vapeurs d’huile diffusant de la pompe a huile dans le systeme & vide.
127/R
Laboratory Apparatus for the Distillation of Oils for Diffusion Pumps
0
Pump Oils of a certain composition have been distilled under vacuum in a laboratory-size column. France. Pumps running on oil treated in the manner described produced a vacuum of the order of 1 x 10-Bmm. Hg. Prior to the introduction of this process the lowest pressure obtainable was 7 x 10-6mm. Hg. Details of the method and the equipment required are given. Sommaive : Description d’un procede de distillation de pompage en partant d’huiles convenables.
de laboratoire
recommande
pour la preparation
Article by ~tiAZ$ll& Le Vide I, Ju’y$;t. 1951
de fluides
Silicone Oil Vapour and Secondary Electron Emission
128/E
United Kingdom. Secondary electron emission in a system evacuated by silicone oil diffusion pumps has been studied. Determining the ‘ sticking ’ potential of a fluorescent powder the initial values obtained were of the order expected but under electron bombardment the secondary emission began to fall off within 30 minutes and the sticking potential dropped from 30 to 1.5 kV. In another series of experiments various surfaces in an ‘ orbital beam ’ electrode system have been investigated. One of the materials examined was a mixture of magnesium and barium oxide. The source of primaribs was a tungsten filament. Heating the secondary cathode to 1,OOO”Cand allowing it to cool the secondary emission coefficient dropped from an initial value of 5 to 1.5. A dark deposit could be noticed on the secondary cathode and staining of a similar kind on the anode The nature of the deposit was not determined. and glass bulb of the ionisation gauge. No such effects could be found on thermionic emitters. As a result of these experiments it is believed that silicone settling on the bombarded electrode may be decomposed, but thermionic emitters are too hot to permit the formation of a silicone film. Sommaire d’electrons
Letter by A. Lempicki & A. B. McFarlane Nature 167, 195.1951 81#814
: Les effets d’huile silicone utilisee comme fluide dans des pompes & diffusion sur l’emission secondaire dans les systemes CvacuCs sont Ctudies.
129/11
Vacuum Refrigeration
0
See Abstract
No.
: 169/111 130/R
Machined Carbon Products See Abstract
No.
: 149/11
21 -
GAUGES
-
21
131/R
Vacuum Gauge Using Alpha-Rays This is a short note describing the design and performance of a gauge similar in construction to the France. alphatron gauge. Polonium is used as the source of alpha-particles. The gauge can be employed for pressure readings in the range of 10-l to 10amm. Hg. It is specially recommended for the measurement of the pressure of corrosive gases, for instance halogens and is, therefore, particularly suitable for use in connection with the production of Geiger counters. Finally, it could serve as an indicator of the partial pressure exercised by a component gas in a gas mixture, e.g. neon in a neon-argon mixture. Sommaire
Note br G. Gimen& & J. Labeyrie J. Phys. Radium 12, Oct. 1951 64A85A
: Etude de la construction et des performances d’une jauge 8. ionisation & particle alpha.
-I October, 7951
Vacuum
321