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1796. The production of ultrahigh vacuum
Classified
abstracts
1796-1806
contents were analyzed by means of an Omegatron. The relevant spectra are presented. H Hoch, Vukuurn-Technik, 16 (7), Sep? 1967, 159-167, (in German). 20 1796. The production of ultrahigh vacuum.
(Great Britain) The production of pressures of about 1O-g torr in large vessels by the use of clean pumps is discussed. Evacuation is carried out using a carbon-bladed rotary pump, two sorption pumps used independently of each other, a triode getter-ion pump and a titanium sublimation pump. The pumpdown process is discussed with special emphasis on the outgassing. T J Coutts, Lab Practice, 16 (6), 1967, 719-733. 20 : 32 1797. Mechanical design of the baseball coil and plasma-trapping chamber. (USA) Basic calculations and design considerations of the “baseball” seam conductor and its corresponding vacuum chamber for plasma experiments in the Alice device are described. A discussion is presented of a structural failure encountered during magnet operation, and corrective measures which were taken. R E Bathgate and W S Neef, Rep UCRL-70026, (Califbrnia Univ, Livermore,
Lawrence
Radiation
Lab).
20 1798. Vacuum system for an experiment on the flow of oxygen across
a silver barrier and through a capillary. (USA) The continued growth of vacuum technology as applied to research and engineering makes it important that students become acquainted with a typical vacuum system. The system described can be applied to the determination of the quantity of gas flowing through a cylindrical tube and to investigations on the passage of gas across a solid barrier (permeation). The vacuum system has been designed in such a way that the experiment can be accomplished in a 2- to 4-hr laboratory period. K M Busen, Am J Phys, 35 (5), May 1967, 398-404. 20 1799. Vacuum furnace for attachment to a low frequency induction furnace. (USA) The inductor unit consists of two metallic casings that together form a passage parallel to the plane of the wall. This receives a coil that forms two branch portions. Electrical insulation is packed between the casings and extends around each of the branches. The end of the second casing can be cleaned separately from the first. Allmanna Svenska Elektr Akt, US Pufenl 3,334,171, Oficial Gaz US Patent Ofice, 841 (l), 1st Aug 1967, 274.
hydrogen vapour pressure curve via the mixed condensate. It is approximately 700 cal/mol. This is greater than the evaporation heat of the pure hydrogen but less than the adsorption energy of hydrogen on metal surfaces. J Hengevoss and E A Trendelenburg, Vacuum, 17 (9), Sept 1967, 499-500. 21 1802. Electrical characteristics
(USA) Ultrahigh vacuum, sputter-ion pumps were investigated to determine the origin and destination of the electrically charged particles constituting the pump current. Secondary electron emission was found to be responsible for a large proportion of the total current and ion energies ranged from 0.5 to 0.8 of the applied pump potential. Departures from linearity in the dependence of pump current on pressure were caused by needle crystals (whiskers) which grow progressively from the pump electrodes. K B Wear, J ApplPhys, 38 (4), 15th March 1967, 1936-1940. 21 1803. Pumping speed and the current of sputter-ion pumps in the region of low pressures. (USSR)
Type NEM-30-2 sputter-ion pump, with pumping speed of 30 litre/sec at lo-” torr and ultimate pressure of 1 x 1Om8torr, was investigated at pressures below 10m6 torr. The pumping speed was measured by the method of the pressure difference on an orifice with known conductivity. It is shown that the dependence of the discharge current-to-pressure ratio on the pressure is very similar to the dependence of the pumping speed on the pressure. E M Rudnitskiy, Pribory 127-l 29 (in Russian).
21 :16 1800. Thermal desorption of argon ionically pumped into glass. (Great Britain) Measurements were made on the release of ion pumped argon from glass. The gas release was measured during heating of the glass after ion injection as the temperature of the glass was raised according to a linear time schedule. Release was measured both without the previous heat treatment of the glass and following constant temperature heat treatments. The shift in the thermal desorption rate temperature function as a result of the previous heat treatments supports the view that ions are trapped with a broad spectrum of activation energies in the glass and not with one or two discrete activation energies. R Konjevic et al, Vacuum, 17 (9), Sept 1967, 511-514.
^. LI 1801. Continuous cryotrapping of hydrogen by argon in the temperature (Great Britain) Hydrogen in the under-saturated condition can condense on cold surfaces if it is mixed with argon. The mixed condensation of argon and hydrogen for condensation surface temperatures in the region between 4.2 and 15°K was investigated. The results of the experiments showed that the trapping ratio, ie the number of argon atoms required to bind one hydrogen atom, rises exponentially with the temperature. In slow heating of the condensation surface, two maxima are observed in the hydrogen partial pressure curve. This behaviour suggests that binding of the hydrogen in the argon condensate takes place with two different binding energies. The binding energy of one of the two conditions is determined by measuring the range between 4.2 and 15°K.
618
Tekh
Eksper,
12 (3), May-June
1967, 21
1804. Cooled titanium sorption pump.
(USSR) The design of type STON-20M titanium UHV pump is described. At the end of the Ti wire a drop of melted Ti (4 mm in diameter) is produced by bombarding the wire with a bent electron beam and Ti is evaporated at the rate of 5 mg/min on to a wall of area 50 dm2, cooled by liquid nitrogen. Thus, all hot parts (excluding Ti drop) can be carefully thermally shielded and the liquid nitrogen consumption is only about 2 litre/hr. Forevacuum, oil diffusion pump with a cold trap is employed. A 100 litre chamber was connected to the titanium pump by a 500 mm ID flange and an ultimate pressure of lOmy torr was obtained without baking and 8x lo-i3 torr after baking the entire system at 400°C. The pressure was measured by type MM-14-M magnetron gauge. The pumping speed is constant in-the range of 5 x l&l” to 10m7torr and-the measured values were: for H,. 2.8x lo4 litre/sec. for N,. 0, and CO. lo4 litreisec and for air 4.5 x lo3 litre/sec. Argon is pumped only by the diffusion pump with an effective speed, on Ti pump flange, of 90 litre/sec. The UHV aggregate containing this Ti pump with fore-vacuum pumps and accessories named AVTO-20-M is commercially available but the manufacturer is not indicated in this paper. N E Biryukova et al, Pribory Tekh Eksper, 12 (3), May-June 1967, _I
21. PUMPS AND PUMP FLUIDS
of sputter-ion pumps
,
_,
_
135-138. 1805. Cold diffusion pump. (USSR) The design of a one-stage diffusion pump using CO, as a working fluid is described. Rarefied CO, was fed into a nozzle with an extension of 400 and was condensed on walls cooled by liquid nitrogen. With pump ID of 110 mm, the quantity of CO, of 0.13 g/set and fore-vacuum pressure 1O-2 torr, a pumping speed of 500 litre/sec and ultimate pressure of 1 x 1O-~6torr were obtained. After 3 working hours the thickness of condensed CO, is about 15 mm and during further running the pumping speed is decreased, Using water vapour instead of CO, in the same pump, the same speed was obtained and the ultimate pressure was 2 x lo-’ torr with a partial pressure of non-condensing gases of 4x 10 -9 torr. The advantage of this pump is that it does not need baffles or cold traps, decreasing the effective pumping speed. L V Falaleev and A B Tsevtlin. Priborv Tekh Eksper, 12 (3). May-June 1967, 1299135 (in Russian). _ 1806. Investigation regime. (USSR)
of cryopump
operation
in the
free
21 molecular
A system containing a cryopump is analyzed and it is shown that the sticking coefficient can be easily computed from the probability of return to the sample of molecules previously released from the sample surface if system walls degassing is negligible. Measuring
abstracts
1796-1806
contents were analyzed by means of an Omegatron. The relevant spectra are presented. H Hoch, Vukuurn-Technik, 16 (7), Sep? 1967, 159-167, (in German). 20 1796. The production of ultrahigh vacuum.
(Great Britain) The production of pressures of about 1O-g torr in large vessels by the use of clean pumps is discussed. Evacuation is carried out using a carbon-bladed rotary pump, two sorption pumps used independently of each other, a triode getter-ion pump and a titanium sublimation pump. The pumpdown process is discussed with special emphasis on the outgassing. T J Coutts, Lab Practice, 16 (6), 1967, 719-733. 20 : 32 1797. Mechanical design of the baseball coil and plasma-trapping chamber. (USA) Basic calculations and design considerations of the “baseball” seam conductor and its corresponding vacuum chamber for plasma experiments in the Alice device are described. A discussion is presented of a structural failure encountered during magnet operation, and corrective measures which were taken. R E Bathgate and W S Neef, Rep UCRL-70026, (Califbrnia Univ, Livermore,
Lawrence
Radiation
Lab).
20 1798. Vacuum system for an experiment on the flow of oxygen across
a silver barrier and through a capillary. (USA) The continued growth of vacuum technology as applied to research and engineering makes it important that students become acquainted with a typical vacuum system. The system described can be applied to the determination of the quantity of gas flowing through a cylindrical tube and to investigations on the passage of gas across a solid barrier (permeation). The vacuum system has been designed in such a way that the experiment can be accomplished in a 2- to 4-hr laboratory period. K M Busen, Am J Phys, 35 (5), May 1967, 398-404. 20 1799. Vacuum furnace for attachment to a low frequency induction furnace. (USA) The inductor unit consists of two metallic casings that together form a passage parallel to the plane of the wall. This receives a coil that forms two branch portions. Electrical insulation is packed between the casings and extends around each of the branches. The end of the second casing can be cleaned separately from the first. Allmanna Svenska Elektr Akt, US Pufenl 3,334,171, Oficial Gaz US Patent Ofice, 841 (l), 1st Aug 1967, 274.
hydrogen vapour pressure curve via the mixed condensate. It is approximately 700 cal/mol. This is greater than the evaporation heat of the pure hydrogen but less than the adsorption energy of hydrogen on metal surfaces. J Hengevoss and E A Trendelenburg, Vacuum, 17 (9), Sept 1967, 499-500. 21 1802. Electrical characteristics
(USA) Ultrahigh vacuum, sputter-ion pumps were investigated to determine the origin and destination of the electrically charged particles constituting the pump current. Secondary electron emission was found to be responsible for a large proportion of the total current and ion energies ranged from 0.5 to 0.8 of the applied pump potential. Departures from linearity in the dependence of pump current on pressure were caused by needle crystals (whiskers) which grow progressively from the pump electrodes. K B Wear, J ApplPhys, 38 (4), 15th March 1967, 1936-1940. 21 1803. Pumping speed and the current of sputter-ion pumps in the region of low pressures. (USSR)
Type NEM-30-2 sputter-ion pump, with pumping speed of 30 litre/sec at lo-” torr and ultimate pressure of 1 x 1Om8torr, was investigated at pressures below 10m6 torr. The pumping speed was measured by the method of the pressure difference on an orifice with known conductivity. It is shown that the dependence of the discharge current-to-pressure ratio on the pressure is very similar to the dependence of the pumping speed on the pressure. E M Rudnitskiy, Pribory 127-l 29 (in Russian).
21 :16 1800. Thermal desorption of argon ionically pumped into glass. (Great Britain) Measurements were made on the release of ion pumped argon from glass. The gas release was measured during heating of the glass after ion injection as the temperature of the glass was raised according to a linear time schedule. Release was measured both without the previous heat treatment of the glass and following constant temperature heat treatments. The shift in the thermal desorption rate temperature function as a result of the previous heat treatments supports the view that ions are trapped with a broad spectrum of activation energies in the glass and not with one or two discrete activation energies. R Konjevic et al, Vacuum, 17 (9), Sept 1967, 511-514.
^. LI 1801. Continuous cryotrapping of hydrogen by argon in the temperature (Great Britain) Hydrogen in the under-saturated condition can condense on cold surfaces if it is mixed with argon. The mixed condensation of argon and hydrogen for condensation surface temperatures in the region between 4.2 and 15°K was investigated. The results of the experiments showed that the trapping ratio, ie the number of argon atoms required to bind one hydrogen atom, rises exponentially with the temperature. In slow heating of the condensation surface, two maxima are observed in the hydrogen partial pressure curve. This behaviour suggests that binding of the hydrogen in the argon condensate takes place with two different binding energies. The binding energy of one of the two conditions is determined by measuring the range between 4.2 and 15°K.
618
Tekh
Eksper,
12 (3), May-June
1967, 21
1804. Cooled titanium sorption pump.
(USSR) The design of type STON-20M titanium UHV pump is described. At the end of the Ti wire a drop of melted Ti (4 mm in diameter) is produced by bombarding the wire with a bent electron beam and Ti is evaporated at the rate of 5 mg/min on to a wall of area 50 dm2, cooled by liquid nitrogen. Thus, all hot parts (excluding Ti drop) can be carefully thermally shielded and the liquid nitrogen consumption is only about 2 litre/hr. Forevacuum, oil diffusion pump with a cold trap is employed. A 100 litre chamber was connected to the titanium pump by a 500 mm ID flange and an ultimate pressure of lOmy torr was obtained without baking and 8x lo-i3 torr after baking the entire system at 400°C. The pressure was measured by type MM-14-M magnetron gauge. The pumping speed is constant in-the range of 5 x l&l” to 10m7torr and-the measured values were: for H,. 2.8x lo4 litre/sec. for N,. 0, and CO. lo4 litreisec and for air 4.5 x lo3 litre/sec. Argon is pumped only by the diffusion pump with an effective speed, on Ti pump flange, of 90 litre/sec. The UHV aggregate containing this Ti pump with fore-vacuum pumps and accessories named AVTO-20-M is commercially available but the manufacturer is not indicated in this paper. N E Biryukova et al, Pribory Tekh Eksper, 12 (3), May-June 1967, _I
21. PUMPS AND PUMP FLUIDS
of sputter-ion pumps
,
_,
_
135-138. 1805. Cold diffusion pump. (USSR) The design of a one-stage diffusion pump using CO, as a working fluid is described. Rarefied CO, was fed into a nozzle with an extension of 400 and was condensed on walls cooled by liquid nitrogen. With pump ID of 110 mm, the quantity of CO, of 0.13 g/set and fore-vacuum pressure 1O-2 torr, a pumping speed of 500 litre/sec and ultimate pressure of 1 x 1O-~6torr were obtained. After 3 working hours the thickness of condensed CO, is about 15 mm and during further running the pumping speed is decreased, Using water vapour instead of CO, in the same pump, the same speed was obtained and the ultimate pressure was 2 x lo-’ torr with a partial pressure of non-condensing gases of 4x 10 -9 torr. The advantage of this pump is that it does not need baffles or cold traps, decreasing the effective pumping speed. L V Falaleev and A B Tsevtlin. Priborv Tekh Eksper, 12 (3). May-June 1967, 1299135 (in Russian). _ 1806. Investigation regime. (USSR)
of cryopump
operation
in the
free
21 molecular
A system containing a cryopump is analyzed and it is shown that the sticking coefficient can be easily computed from the probability of return to the sample of molecules previously released from the sample surface if system walls degassing is negligible. Measuring