1590. Continuous vacuum casting—experimental system (France)

Classified abstracts 1579-1590 on 1-hexene, losses involving excitation to the lowest triplet state are also prominent near threshold. P B Merkel and W H Hamiil, J Chem Phys, 55 (3), 1st August 1971, 1409-1413. 33 1579. An experimental device for measuring the diameter of the electron beam of a klystron. (USSR) A vacuum device is described which permits visual observation and (with the aid of a special microscope) measurement of the geometric dimensions of electron beams with small diameters ranging from 1 to 3 m m under conditions corresponding to real devices. A D Zakurdaev et al, Elektron Tekh Elektron SVCh, 2, 1971, 126-128

V A Nikitiuskiy and D A Noskov, Sb Rab Aspir Tomsk Inst Radio Elektron Tekh, 1, 1969, 227-230 (in Russian).

(in Russian).

Ukrainian). 33

1580. Source of radially converging ion beams. (USSR) A gas-discharge source with a hollow ring cathode is described which produces a radially converging ion beam. The hollow cathode consists of two steel plane ring electrodes and a cylinder with an opening for outlet of ions. The copper anode has the form of a ring embracing the cathode. Gas is admitted through an opening in the anode and the magnetic field is produced by a 20- to 25-turn solenoid. Theanode, cathode and solenoid are water-cooled. During continuous operation of the ion source, the maximum discharge current reached 500 mA at 8 x 10-3 torr. The ion current to a collector placed in the axis of the system was 120 m A under these conditions. The ion source can be used for treatment of components of ionic devices, for machining of apertures in cylinders of hard and refractory metals, and for obtaining thin films by cathodic sputtering. D A Noskov and A S Shangin, Sb Rab Aspir Tomsk lnst Radioelektr Elektron Tekh, 1, 1969, 217-220 (in Russian). 33 1581. Characteristics of electron beams in forevacuum. (Germany) The performance of electron guns, intended for technological electron-beam equipments, in conditions of forevaeuum at pressures above 10-4 tort, is investigated. From the practical point of view, it is necessary to know the total loss of energy of the electron beam, the energy transferred to the target, and also the distribution of energy density in the bombarding electron beam in dependence on the pressure. The results of measurements are presented which were performed using the methods of collector current and calorimetry. Photographs of welds performed at different electron beam parameters and pressures are presented. A n analytical equation for the distribution of the power density in the electron beam is given for conditions of considerable influence of residual gas. S Schiller et al, Schweisstechnik, 21 (1), 1971, 11-16 (in German). 33 1582. Some characteristics of electron and discharge current flow through long tubes. (USSR) Volt-ampere and probe characteristics of vacuum and gas-filled diodes with anode-cathode distances up to 50 cm are measured and analyzed. The residual gas pressure in the vacuum diodes was 5 x 10-6 tort and the gas diodes were filled with argon in the pressure range 5 x 10-2 to 10 torr. V N Kostin and N I Vinokurov, Radiotekh Resp Mezhved Nauch Tekh Sbor, 12, 1971, 98-99 (in Russian). 33 1583. Experimental investigation of a short electron gun. (USSR) Characteristics of ribbon electron beams formed by short electron guns, type M, are investigated experimentally. Yu N Yurkin and E S Vakshlyak, Vopr Elektron Tekh, Saratov 1971, 165-170 (in Russian). 33 1584. Outlet of electrons along the magnetic field from discharge with ring cathode. (USSR) A gas-discharge device with a ring cathode is described which is used in magnetic electric-discharge pressure gauges with cold cathode. The data on outlet of electrons parallel to the axis of the device along the magnetic field and extraction of electrons to a collector by means of the electric field, are presented. For experimental purposes, a discharge device was manufactured which contains a brass cathode soldered to steel plates. A molybdenum rod supported by a ceramic insulator was used as an anode. A permanent magnet produces a magnetic field with intensity 500 Oe between the cathode plates. It is experimentally demonstrated that the discharge device can be used as a low-current electron source with stable operation at 10-4 to 10-5 torr.

33 1585. Ignition conditions in electron gun operation in a gaseous medium. (USSR) An approximate calculation of the emission current which can be obtained from an electron-gun cathode in the presence of ion space charge is derived. A criterion for arc discharge ignition is presented. The calculations are experimentally verified. Recommendations on the choice of parameters and construction of the gun for prevention of arc discharge ignition are presented. S M Levitskiy and D Yu Sigalovskiy, Fiz Elektron, 3, 1970, (in 33 1586. Magnetic and adsorption properties of isoelectronic semiconductors based on germanium. (USSR) Magnetic susceptibility of Ge, GaAs, ZnSe and CuBr and its variation due to adsorption processes are experimentally investigated. I A Kirovskaya and A A Zheltonozhko, Neorg Mater, 7 (6), 1971, 921924 (in Russian). 33 1587. Investigation of the ion bombardment of glass by active gas in a glow discharge. (USSR) Effect of the initial stages of discharge on glasses of different chemical composition is investigated. Optical glasses, fused silica and glass filaments are examined with the aid of an electron microscope. The vacuum system was evacuated by a mercury diffusion pump with a liquid nitrogen trap. Discharge voltage was 2 kV, current, 150 mA, and air pressure 5 x 10-~ torr, with aluminium electrodes. The treatment time ranged from 5 to 30 minutes. The samples were placed outside the discharge space. Under these conditions glass is bombarded only by random slow ions and by neutral and excited molecules. It is found that chemical reactions occur between the glass components and the discharge gas. The corrosion patterns formed are characteristic for glasses of a given composition and can be explained by chemical heterogeneity of the glasses. This effect can be utilized to investigate the chemical heterogeneity of glasses and provides informations on the form, dimensions and distribution of the heterogeneities. Improved resistance to atmospheric corrosion in glasses treated by discharge, is due to deposition of an oxide layer of electrode metal on the surface. V M Egorov et al, Neorg Mater, 7 (6), 1971, 1035-1039 (in Russian). 33 1588. Non-linear volt-ampere characteristics of p-type germanium. (USSR) Field emission characteristics of p-type germanium, with resistivity 80 and 30 ohm cm, are investigated using simultaneous measurement of Fowler-Nordbeim plots, voltage drop on the crystal and imaging of field emission patterns in a field emission microscope. G N Fursey and R Z Bakhtirin, Vest Leningr Univers, No 22, 1970, 6672 (in R~tssian). 37. METALLURGY, INORGANIC CHEMISTRY, ANALYTICAL CHEMISTRY 37 1589. Analysis of molten alloys under vacuum by an x-ray emission spectrometer. (France) The system described permits continuous analysis of an alloy during its build-up in an electron beam furnace, without interrupting or disturbing this build-up. With this in situ analysis, complex materials of any predetermined composition may be obtained. Another experimental arrangement permits direct study of solidification by microprobe analysis. As an example, the method for the study of unidirectional solidification of eutectic alloys is presented. B Dalgne and F Girard, Le Vide, 26 (152), March-April 1971, 69-75

(in French). 37 1590. Continuous vacuum casting--experimental system. (France) A machine under development for the casting of uranium rods as fuel elements for the French Graphite Gas reactors, combines vacuum induction melting and continuous casting with continuous withdrawal of the ingot from the vacuum chamber to the open air. The pilot-scale device is described including the pumping system, control equipment for the flow rate of molten metal, dynamic vacuum seal, secondary cooling, and the withdrawal system. 625

Classified abstracts 1591-1607 C Guichard and J C Sorer, Le Vide, 26 (152), March-April 1971, 76-79

(in French). 37 1591. Dependence of dislocation density on the growth rate of copper single crystals. (USSR) The dependence of the dislocation density on the growth rate of copper single crystals is investigated. The copper single crystals were grown from the melt in vacuum at 1 × 10-4 to 5 × 10-~ torr using the Czochralski method. V V Sanadze et al, Izv VUZ Fiz, No 7, 1970, 127-130 (in Russian). 37 1592. Investigation of the conditions for production of lanthanum hexaboride of increased purity and stoichiometrie composition. (USSR) The mechanism and conditions for the production of lanthanum hexaboride of high purity and stoichiometric composition, by reduction of La~O3 by boron in vacuum, are described. The optimum temperature of 1900°C at 5 per cent boron excess and pressure of 1 × 10-z torr in the furnace are determined. It is shown that during high-temperature reduction in vacuum at 10 -4 to 10 5 tort, refining of the lanthanum hexaboride takes place. G A Meerson et ai, Neorg Mater, 6 (7), 1970, 1219-1223 (in Russian). 37 1593. Reactions of Na ÷, K + and Ba ÷ ions with 03, NO and H~O molecules. (USA) The above reactions were studied in a drift tube-mass spectrometer apparatus. The rate constants or upper limits are tabulated. The consequences of the results for the D and E region of the upper atmosphere are briefly discussed. R Johnson et al, J Chem Phys, 55 (1), 1st July, 1971, 186-188. 37 1594. Growth of CdTe crystals from the vapour phase by vacuum sublimation. (USSR) Causes prohibiting the control of the type and magnitude of conductivity during the growth of CdTe crystals from the vapour phase by vacuum sublimation in a closed volume are investigated. The preparation technique for CdTe crystals is based on mass transfer of CdTe in a determined thermal gradient by diffusion through the gas phase in a closed volume. The arrangement for vacuum sublimation of CdTe is described. It is found that vacuum sublimation is suitable only for the preparation of CdTe crystals with p-type conductivity and with various deviations from stoichiometry. S A Medvedev and Yu V Klevkov, Neorg Mater, 7 (5), 1971, 753-756

(in Russian). 37 1595. Manufacture and properties of lithium fluoride ingots. (USSR) Lithium fluoride ingots were manufactured by melting the powdered salt in a vacuum furnace at a pressure of 10 to 20 tort, in graphite crucibles. It is shown that the ingots can be used as a source of optical materials. T V Tuytuynnikova et al, Neorg Mater, 7 (3), 1971, 525-526 (in

Russian). 37 1596. Gas-transport reactions of some rare-earth element orthophosphates. (USSR) The mechanism of LnPO4 transport during the reaction with PCI~ is explained and it is shown that gaseous chlorine serves as transport medium and PCI5 only as a chlorine source. An arrangement for filling an evacuated ampoule with PC15 in a vacuum system is described. V P Orlovskiy et al, Neorg Mater, 7 (6), 1971, 971-978 (in Russian). 37 1597. Thermodynamics of fabrication processes and electrical properties of CdS-CdO single crystals. (USSR) Thermodynamic functions of processes of oxygen interaction with CdS were evaluated and CdS-CdO single crystals with small amounts of CdO were synthesized by the technique of vapour condensation in a closed evacuated ampoule. To avoid diffusion of atmospheric oxygen through the quartz walls, the ampoule was placed in argon ambient. O F Lutskaya et al, Neorg Mater, 7 (6), 1971, 930-933 (in Russian). 37 1598. Simultaneous determination of nitrogen and oxygen in titanium and its alloys by isotopic spectrometry. (USSR) An isotopic spectrometer method for simultaneous determination of the nitrogen and oxygen contents of titanium and its alloys is des-

626

cribed. The sensitivity is 5 × 10-4 per cent for oxygen and 10-4 per cent for nitrogen. G K Dudich et al, Zavodsk Lab, 37 (4), 1971, 43~437 (in Russian). 37 1599. New hygrometers for mieroconcentrations of moisture in gases. (USSR) Main characteristics and design features of new Russian instruments for measurement of water vapour content in gases are discussed. E A Gershkovich et al, Izmerit Tekh, No 6, 1971, 76-77 (in Russian). 37 1600. Purification of selenium and tellurium using a method based on their volatility. (USSR) It is demonstrated that using vacuum rectification, very pure selenium and tellurium can be obtained. G P Ustyugov et al, Nizkotemper Termo Mater, Kishinev 1970, 5-11

(in Russian). 37 1601. Growth of CdSe single crystals from the vapour phase in nonstoiehiometric and stoichiometric ambient. (USSR) Results of analysis of CdSe single crystal growth using the technique of static sublimation are presented. R V Baubinas et ai, Liet Fiz Rinkinys, 10 (6), 1970, 907-915 (in

Russian). 37 1602. Investigation of the vacuum melting of copper. (USSR) Technique and results of mass-spectrographic investigations on the vacuum melting of copper are presented. Data on the course of gas evolution during melting are obtained. The investigations included leakage and its influence on ambient composition in the furnace, kinetics of evolution of all components of the furnace atmosphere during copper melting, evaporation of additives in copper during vacuum melting, and the dependence of the oxidation potential of the furnace on the ambient gas. D S Barbarash, Elektron Tekh Tekhnol Organiz Proiz, 8, 1970, 68-75

(in Russian). 37 1603. Gas-chromatographic method of measurement of surface area of carbon black. (USSR) A gas-chromatographic method for determination of specific surface area of carbon black is described in which hydrogen was used as carrier gas and nitrogen as adsorbate. The results of measurement are in agreement with the data obtained by the BET method. A vacuum treatment of carbon black is recommended before measurement to remove volatile contaminants. I L Maryasin et al, Zavodsk Lab, 37 (1), 1971, 41-43 (in Russian). 37 1604. Apparatus for investigation of the time dependence of the tensile strength of glass and polymer fibres in vacuum and different ambients. (USSR) An apparatus for investigation of the life-span of glass fibres is described which enables simultaneous investigation of 20 samples of different length at different static loads in vacuum or in various gases. A V Zakharov and A B Sidorov, Zavodsk Lab, 37 (4), 1971, 491492

(in Russian). 37 1605. Apparatus for fatigue investigations at temperatures of 1.5300°K. (USSR) A simple apparatus for investigation of the fatigue of materials in condensed gas ambients and the influence of high vacuum and low temperatures on the fatigue properties of materials is described. I A Gindin et al, Zavodsk Lab, 37 (4), 1971, 488-489 (in Russian). 37 1606. Some physical properties of iron borides. (USSR) Some physical properties of iron borides FeB and Fe2B, prepared by synthesis in vacuum, are investigated. Thermionic properties were determined in a glass device at a residual gas pressure of 10 -7 torr. The work functions at 1600°K were 3.3 eV for Fe~B and 3.6 eV for FeB. The sublimation energies were determined with the aid of a mass spectrometer and found to be 86.9 kJ/mol for Fe2B and 214 k J/tool for FeB. I I Kostetskiy et al, Neorg Mater, 7 (6), 1971, 951-955 (in Russian). 37 1607. Electrical resistivity of LaCrO3, NdCrO3, SmCrO3 and YCrO3 at high temperatures. (USSR) Electrical resistivity of alkaline earth chromates is investigated in vacuum at 10 2 to 10-2 torr and at high temperatures up to 2300°C.