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Classified abstracts 734-748a dropping Hg pump with a calibrated capillary in which the gas ismeasured quantitatively.J Hudek and A Dubansky, Chem L&y, 59 (IO), 1965, 1230, (i nCzech). 21734. Method for measuring the warm-up and cooldown characteristicsof oil-diffusion pumps. (USA)American Vacuum Society Standard (tentative) describes the pro-cedures for determining the warm-up and cool-down characteristicsof diffusion pumps.Anon, J Vat Sri T ech, 3 (I ), Jan-F eb 1966,32-33. 21735. A new ultrahigh vacuum pump. (USA)The theory of a highly rarefied cascade flow has been presented anda proposal for a new axial-flow (or radial flow) pump (or compressor)in the free-molecule range has been made. An unconventionalcascade has been suggested which will produce an extremely highcompression ratio (up to 30,000) in a single stage at very high bladespeed. This new pump (or compressor) can be used to reach a veryhigh vacuum state.Y Wu, Princeton Uni versity, NJ, Gas Dynamics L aboratory, 16pages.

21736. Analysis of thin films of tantalum reactively sputtered in nitrogenatmosphere. (USA)Electron diffraction studies were made of thin films of tantalumreactively sputtered in nitrogen.E A Buvinger, Appl Phys Letters, 7 (I ), 1965,14.

21737. A reliable non-contaminating gas circulation pump. (USA)A reliable maintenance free, non-contaminating gas circulation pumpwas developed for use in re-circulation reactor systems.R P Chambers et al, J Catalysis, 4,1965,625.

21738. Calculation of the pressure characteristics for centrifugal pumpsand fans at zero flow rate. (USSR)A A Levin and V I Polikoskii, Akad Nauk USSR, I zvestia, En ergitika iTransport, 1965.129-133, (in Russian).

21 131739. Steam-jet vacuum pumps and their use for the vacuum degassingof steel. (Czechoslovakia)Energy equations are derived for the specific steam consumption andefficiency of steam-jet vacuum pumps and curves are shown for bothsingle- and multi-stage systems. Criteria for choice of size and controlof stages in multi-stage processes are obtained from the equations.Pump operating procedure with particular reference to the vacuumtreatment of steel is described. Aspects of plant construction andassembly for vacuum treatment, energy supplies, and determinationof intake capacity are discussed.T Messing, Hu tnicke Li sty, 19 (12), 1964. 851-857. (in Czech).

21740. Pumps for nuclear service. (USA)General survey of pumps used in nuclear technology.A L Bunke and R E Ball, American Power Conference, Chicago, April1965, I Spages.

21 : 32741. Nuclear reactor. Design of fluid-driven mechanical pump. (GreatBritain)A fluid-driven mechanical pump is driven by the primary reactorcoolant and is particularly applicable to integral type reactors inwhich the primary coolant circulating pump must be located withinthe reactor vessel. The reactor includes a core housed within thereactor vessel and conduits penetrating the vessel for energization ofthe pump by operating fluid. The pump is mechanically linked to thefluid-driven motor housed in the vessel and immersed in the primarycoolant.E W Sidebotham et al, Briti sh Patent 996,784, June 1965, fil ed18 July 1963.

21 :47742. Chemical support for the controlled thermonuclear programme.(USA)Surface diffusion was indicated to be the dominant mechanism bywhich vacuum systems become contaminated with diffusion pumpoil. The origin of methane in high-vacuum systems was indicated tobe the reaction of carbon atoms on the surface of titanium metal

with ionically pumped hydrogen. The reaction of water vapour withtitanium surfaces was found to produce H, and CO. Results on othersystems are reported.R A Strahlow and D M Richardson, Oak Ridge National Laborator >Report 3789,1965,334-340.

21 :41743. Corrosion in mercury diffusion pumps. (Australia)Mercury diffusion pumps employed for the outgassing of electronicvalves at the Miniwatt Valve factory, in Australia, have been subjectto severe corrosion in the water-jacketing of the mercury trap.Several corroded specimens were dismantled, sectioned and examinedmicroscopically, with compositions determined by electron probemicroanalysis. Electrochemical potentials of clean, polished samplesof the materials were measured in de-ionized water and in samplesof cooling and make-up water. The effect of various inhibitor addi-tions on these potentials was also measured. The results led to theconclusion that the all-stainless-steel construction of water-jacketand trap, combined with chromate and trisodium phosphate additionto the cooling water, will successfully prevent corrosion providedthat the chromate concentration is maintained at 2 lb/l000 gallonsor above.E W Gooden, Corr osion in transport and industry, 6th Ann ConfAustral asian Corr osion Assoc. 15-19 Nov 1965, dpages.

21 : 33744. Experiments with a liquid helium cryopumped extreme highvacuum. (USA)To produce an ultra-clean environment in simulating lunar surfaceand interplanetary space conditions, a liquid helium cryopumpedvacuum system was built to achieve pressure of 10~ ? torr. Cryogenicsis employed to make outgassing from the test space walls negligibleby cooling them to near 80K, and to provide high pumping speedsat low pressures by a cryopumping surface adjacent to the test surfacemaintained at 4.2K. Boil-off liquid nitrogen and helium providesthe necessary refrigeration. Discussed are experiments to achieve lowtemperatures, H, injection at the warm end of the inner vessel, andpumping nitrogen and hydrogen from the test space.R W Moore, Jr, Sixth An nual Symposium on Space EnvironmentalSimulation, St Loui s, Missouri, May 1965, I 7 pages.

21 141745. Continuous zeolite vacuum apparatus for oil-free pumping.(USSR)The design of a zeolite sorption apparatus for continuous operation,which can maintain a pressure of lo-* to 1O-4 torr in volumes ofIO-100 litres is described, Data are given for the sorption capacity atlow pressure.EN Martinson et al, Pribory i Tekh Eksper IO (4). 1965, 154-160.

21 :22746. Quantitative spark source mass spectrometry using cryosorptionpumping. (USA)The simultaneous estimation of a wide variety of impurity elements(both metals and non-metals) in the ppm range in NBS Fe sampleswith an average precision and accuracy of 120 per cent for oneanalysis consisting of a single graded series of exposures is described.Most of the improvement is achieved through the use of a newcryosorption pump located in the source chamber near the sparkingsample in order to lower and maintain constant source pressure.W L Harrington et al, Anal Chem, 37 (12), Dee 1965, 1480-1484.

21 :17747. The dynamics of cryosorption pumping. (USA)A technique has been developed for the rapid injection of gas samplesinto a low pressure system (Knudsen regime) and for faithfullyrecording the consequent changes in pressure. The experimentalprocedure may be used for measurement of initial rates of adsorptionon a millisecond time scale, and in this investigation was used fordynamically testing the speed of cryosorption pumping of air, Ar,and H, by activated charcoal at liquid N,.S H Bauer and P Jeffers, Cornell Un iversity, I thaca, NY, Ott 1965,NASA-CR-314, I Zpages.

21 : 23748. Simple differential pumping stage for connecting high to ultrahiih-vacuum systems. (USA)Measurements have been made of the N, pressure ratio across aconnecting stage as a function of the nitrogen exposure on the highpressure side. The stage consisted of a titanium evaporator in a

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