907. Gas purifier for plasma generator and mass-spectrometric analysis of trace impurities

Classified abstracts 895-907 16 895. Diffusion of hydrogen through palladium. (USA) Diffusion constants were determined at various temperatures and pressure utilizing a variety of techniques, including electrochemical measurements. Results are tabulated and some models for H~ diffusion are suggested. A C Makrides and D N Jewett, Engelhard Ind Tech Bull, 7, 1966, 51-54. 16 896. Diffusive processes in a solid during tempering. (Great Britain) The rate at which diffusing species cross the surface boundary of a semi-infinite solid during heating of the solid at a constant temperature rise rate is calculated where the initial concentration of species is assumed to be located at a place p lattice units below the surface. The temperature at which this rate reaches a maximum, the temperature width of the rate/temperature curves and the ability to distinguish between rate data when the diffusing species may possess differing activation energies for diffusion are explored. Distributed initial concentrations are also considered and it is shown how the initial concentration distribution can be derived from diffusion data during the tempering cycle. G Farrell and G Carter, Vacuum, 17 (1), Jan 1967, 15-20. 18. GASEOUS ELECTRONICS 18 : 16 Investigation of adsorption and electron emission of caesium layers on tungsten single crystal. See abstract number 888. 18 : 16 Lithium adsorption on tungsten single crystal faces coated by sorbed film of oxygen. See abstract number 889. 18 897. Annular plasmas produced by rotating magnetic fields. (Great Britain) A rotating magnetic field was applied to a cylindrical plasma in a discharge tube whose walls were electrically conducting in the azimuthal direction, which imposed the constraint that the net a-dal magnetic flux in the tube remained constant. A theoretical analysis of the system predicts that the plasma should be confined in an annular configuration, and this was confirmed experimentally by observations using magnetic probes, an image-converter camera and a laser interferometer. A detailed description of the circuits used to preionize the plasma and to produce the rotating field is appended. (Authors). P A Davenport et al, UKAEA Res Rept CLM-R65, Aug 1966, 26 pages. 18 898. Are discharge at low pressures in a magnetic field. (USSR) The drift instability of plasma in arc discharges in H2 and N2 at l0 4 to 10-2 torr was investigated with regard to the transition from arc initiation to stationary arc conditions for pulse discharges. M A Vlasov, Zh Tekh Fiz, 37 (1), Jan 1967, 67 71 (in Russian). 18 899. Emission properties of plasma produced in a vacuum spark. Part 2. Electron beams. (USSR) Emission properties of vacuum spark plasma during the production of high current electron beams was investigated. Some irregularities are indicated and the probable mechanism is discussed. A microsecond electron pulse of 1,000 A from an emitting surface of 5 cm 2 was obtained. K V Suladze and A A Plyutto, Z Tekh Fiz, 37 (1), Jan 1967, 72-78 (in Russian). 18:22 900. Cold cathode Penning discharge at low pressure. (USSR) Equations for the discharge current, space charge anode layer thickness, potential distribution and electron density are given for the Penning discharge at pressures below 10 4 torr, assuming that electron diffusion is transverse to the magnetic field. To obtain more quantitative agreement with experimental data, the influence of collisions of electrons with neutral atoms must be taken into account, but the method presented expresses the phenomenological basis of Penning, magnetron or inverted-magnetron vacuum gauges. Yu S Popov, Zh Tekh Fiz, 37 (1), Jan 1967, 118-126 (in Russian). 18 901. Reflex discharge in a weak magnetic field. (USSR) The influence of linear dimension on characteristics of the reflex discharge in the intensely growing regime was investigated. Experiments were performed on He at l0 4 to 10 z torr. The non-uniform

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distribution of the fast electron density, which causes some irregularities, was observed. E T Kucherenko and V A Saenko, Zh Tekh Fiz, 37 ( I ), Jan 1967, 112 117 (in Russian). 18 902. On the measurement of energy distribution of electrons in the presence of plasma noise. (USSR) The modified Crawford-Garscadden method is described for probe measurements of electron energy distribution in the positive column of a glow discharge, with a lesser sensitivity to the plasma noise. Experimental values are given for discharges in Hg-Ar and Hg-Kr mixtures. Yu M Kagan ct al, Zh Tekh Fiz, 37 ( 1), Jan 1967, 127-130 (in Russian1. 18 903. Field emission of electrons from metals with non-metallic films. (USSR) The mechanism of field emission of tungsten coated with a germanium monolayer or very thin film is discussed. It is shown that the Dobretsov's interpretation of known experimental results, based on Gurney's theory, is not valid for semiconductor monolayers. N V Mileshkina and I L Sokol'skaya, Fiz TverdTela, 8, (11) Nov 1966, 3163-3166 (in Russian). 18 904. On the existence of minimal work functions of film cathodes. (USSR) The fol!owing systems were investigated: barium and calcium thin films on tungsten and tantalum; niobium on rhenium; and caesium on tungsten and rhenium. Minima of the work functions were observed even in the purest conditions, below 3 × 10 10 torr. Duration of experiments was less than 20 minutes. The purity of the evaporation material was measured by a mass-spectrometer and the basic cathode material was heated near to its melting point (eg tungsten to 3,300°K). Gas adsorption exerted an influence on the work function only at pressures above 10-7 torr. However, minima were not observed on substrates having a porous surface eg barium thin films on tungsten powder or on tungsten heated to 3600°K when damage to the surface structure occurred. E A Tishin and B M Tsarev, Fiz Tverd Tela, 8 (11), Nov 1966, 3181 3186 (in Russian). 18 905. Reflex discharges at low pressure. (Czechoslovakia) Investigations of reflex discharges with hot and cold cathode in H2, He, Ar and Kr at pressures of 10-3 to 10 8 torr and with magnetic fields of 0-300 Oe are described. It was found that in reflex discharge with a hot cathode, radial deformation of the potential occurs even at weak magnetic fields. The relationship between the anomalous motion of electrons emitted by the cathode and the experimentally found anomalies in the static and dynamic characteristics (frequency in the Mc/s range) of the suppressed reflex discharge was determined. The changes in the linear dimensions of the discharge were also investigated. E T Kucherenko and V A Saenko, Czech J Phys, B 17 (1), 1967, 67-78 (in English). 18 906. Spectroscopic investigation of gas discharges in argon ion optical quantum generators. (USSR) The charged particle densities and the gas temperature for pulse and continuous wave Ar optical quantum generators were measured for different discharge current densities. With the pulse generator filled by Ar at 6 .~ 10-~ torr and current density 820 A/cm ~ an atomic gas temperature of 6,000°K and electron concentration of 2 ~ 1014/cm~ were observed. V F Kitaeva et al, Dokl Akad Nauk USSR, 172 (2), 1lth Jan 1967. 319 (in Russian).

II. V a c u u m apparatus and auxiliaries 20. PUMPING SYSTEMS 20 907. Gas purifier for plasma generator and mass-spectrometric analysis of trace impurities. (Japan) The performance of the gas purifier installed in the MACETIE (a device for plasma physics research, aimed at controlled thermonuclear fusion) at Nagoya University, is described. The purifier was equipped with precision pressure gauges and thermometers to control