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634. Surface interactions of iodine vapour with tungsten
Classified abstracts Classified
abstracts
625-635
on this
625-779
page
Editor’s note The label immediately following the title of each item denotes country or origin end of each abstract indicates country of origin of work (where known).
I. General vacuum
science and engineering
10. VACUUM SCIENCE AND TECHNOLOGY 10 625. Decade of advances in vacuum equipment and technology. (USA) Improvements in construction and application of vacuum gauges, windows, valves, high vacuum pumps, sputter-ion pumps, getter-ion pumps, sublimation pumps, turbomolecular pumps, cryosorption pumps, cryogenic pumps, and vacuum seals are discussed. T H Batzer and R F Bunshah, Rep UCRL-10369, June 1967,48 pages (Sci Tech Aerospace Reps, 5 (22), 4056, N67-37710). 14. KINETIC THEORY OF GASES
I4 626. Effusion. I. Angular number distributions of gaseous CsCl from a near-ideal orifice into vacuum. (USA) The angular number distributions of CsCl (g) from a double-oven effusion cell with a near-ideal orifice have been measured as a function of the state of the gas, using a surface ionization detector. The orifice was 0.50 mm in diameter with a length of 0.013 mm. The state of the gas was varied over values of the Knudsen number, k, (ratio of meanfree-path to orifice diameter) from 63.38 to 0.16. The experimental results were compared with theoretical predictions. K C Wang and P G Wahlbeck, J Chem Phys, 47 (ll), 1 Dee 1967, 4799-4809. 14 627. Rarefied Row problems by molecular dynamics. (USA) Rarefied flows are studied by considering the detailed motion of the molecules using an electronic computer. The simple example of the relaxation of a two-dimensional hard-sphere gas to equilibrium is considered. It is shown that the equilibrium Maxwell-Boltzmann distribution is reached after few mean free times. (Israel) E Wasserstrom, Rep TA E-69, June 1967,2Opages (Sci Tech Aerospace Reps, 5 (21), 3833, N67-36170).
14
628. Contribution to the kinetic theory of polyatomic gases.
(USSR) Using the generalized Grad’s theory in the 17 momentum approximation, relaxation equations and transfer relations are obtained. As an example, expressions are derived for the slipping velocity and temperature jump in a polyatomic gas near a plane solid wall. V M Zhdanov, Zh Eksper Teor Fiz, 53 (6), Dee 1967, 2099-2108 (in Russian).
14
629. On the possibility of resonance phenomena in the kinetics of
molecular gases. (USSR) Analyzing the viscosity and thermal conductivity in molecular gases like 0,. in perpendicular stationary and varying magnetic or electric fields, it is shown that for certain conditions the transfer and absorption coefficients are of a resonance nature. V D Borman et al, Zh Eksper Teor Fiz, 53 (6), Dee 1967, 2143-2153 (in Russian). 15. FLUID DYNAMICS
15 : 18 630. Transport properties of a nonequilibrium partially ionized gas in a magnetic field. (USA) A moditied Chapman-Enskog technique, developed for a partially ionized gas in an electric field, is generalized to include the effects of a magnetic field. The method allows the electron and heavy particle temperature to differ while requiring all species to have the same macroscopic velocity to zero order. Expressions are obtained for the transport properties of such a gas and a complete set of self-contained magnetohydrodynamic equations are presented. As an example, the
of publication,
and that at the
transport properties of a fully ionized gas, containing a single ion species, are evaluated using the cutoff Coulomb potential. In the limit of equal electron and ion temperatures, the results agree with previous work. R M Chmieleski and J H Ferziger, Phys Fluids, 10 (12), Dee 1967, 252&2530. 15 631. Condensation in a rapidly expanding metal vapour-inert gas mixture. (USA) An investigation of the condensation of metal vapour in an inert carrier gas accelerated through nozzles was carried out. The mixture used is primarily zinc vapour in helium gas. Particle size is determined by means of a shuttered sampling device combined with electron microscope techniques. The condensation onset point is determined by nozzle static pressure measurement. P M Sherman et al, Rep ARL-67-0071, A D-656708, April 1967, 92 pages (Sri Tech Aerospace Reps, 5 (22), 4024, N67--36986). 16. GASES AND SOLIDS
16 : 21 Cryosorption of hydrogen by 12-20°K carbon dioxide cryodeposits. See abstract number 666. 16 : 18 632. Photo-ionization method of determination of adsorbed molecule ionization potentials. (USSR) Ionization potentials of adsorbed molecules on ZnO were determined by the measurements of electrons emitted by the action of infrared monochromatic light beams on the sample. V M Bentsa et al,Pribory Tekh Eksper, 12 (6), Nov-Dee 1967,147-151 (in Russian). 16 633. Adsorption of helium on copper surfaces at 4.2”K.
(USSR) Helium was introduced into a system evacuated by a cryopump with a copper surface at 4.2”K and the pressure in the chamber was measured. At lo-” torr, about lo-’ cm3/cm2 of helium was adsorbed on the walls and at lO-6 torr, 3 x 10-Ocm3/cm2 of He (99.8 per cent of the introduced He) was adsorbed. N P Danilova and A I Shal’nikov, Pribory Tekh Eksper, 12 (6), NovDee 1967, 199 (in Russian). 16 634. Surface interactions of iodine vapour with tungsten.
(USA) The interactions of iodine vapour with a clean tungsten surface were studied by first absorbing the iodine on the tungsten ribbon and then thermally desorbing the adlayer. The composition of the desorption products was determined with a time-of-flight mass spectrometer. No evidence is found for the formation of surface compounds. Only iodine atoms and, at higher coverages, iodine molecules populate the surface. B McCarroll, J Chem Phys, 47 (12), 15 Dee 1967, 5077. 16 635. Surface structures and work function changes in oxygen adsorption on tungsten (100). (USA) It was found that 0, can interact in two distinct ways. At room temperature the adsorption occurs on top of an essentially undisturbed substrate. At higher temperatures 0 atoms can penetrate the surface and form reconstructed layers. Under various conditions several ordered structures are produced and the work function changes. P J Estrup and J Anderson, Rey NYO-3830-1, May 1967, 11 pages (Sci Tech Aerospace Reps, 5 (22), 4127, N67-37234). 293
abstracts
625-635
on this
625-779
page
Editor’s note The label immediately following the title of each item denotes country or origin end of each abstract indicates country of origin of work (where known).
I. General vacuum
science and engineering
10. VACUUM SCIENCE AND TECHNOLOGY 10 625. Decade of advances in vacuum equipment and technology. (USA) Improvements in construction and application of vacuum gauges, windows, valves, high vacuum pumps, sputter-ion pumps, getter-ion pumps, sublimation pumps, turbomolecular pumps, cryosorption pumps, cryogenic pumps, and vacuum seals are discussed. T H Batzer and R F Bunshah, Rep UCRL-10369, June 1967,48 pages (Sci Tech Aerospace Reps, 5 (22), 4056, N67-37710). 14. KINETIC THEORY OF GASES
I4 626. Effusion. I. Angular number distributions of gaseous CsCl from a near-ideal orifice into vacuum. (USA) The angular number distributions of CsCl (g) from a double-oven effusion cell with a near-ideal orifice have been measured as a function of the state of the gas, using a surface ionization detector. The orifice was 0.50 mm in diameter with a length of 0.013 mm. The state of the gas was varied over values of the Knudsen number, k, (ratio of meanfree-path to orifice diameter) from 63.38 to 0.16. The experimental results were compared with theoretical predictions. K C Wang and P G Wahlbeck, J Chem Phys, 47 (ll), 1 Dee 1967, 4799-4809. 14 627. Rarefied Row problems by molecular dynamics. (USA) Rarefied flows are studied by considering the detailed motion of the molecules using an electronic computer. The simple example of the relaxation of a two-dimensional hard-sphere gas to equilibrium is considered. It is shown that the equilibrium Maxwell-Boltzmann distribution is reached after few mean free times. (Israel) E Wasserstrom, Rep TA E-69, June 1967,2Opages (Sci Tech Aerospace Reps, 5 (21), 3833, N67-36170).
14
628. Contribution to the kinetic theory of polyatomic gases.
(USSR) Using the generalized Grad’s theory in the 17 momentum approximation, relaxation equations and transfer relations are obtained. As an example, expressions are derived for the slipping velocity and temperature jump in a polyatomic gas near a plane solid wall. V M Zhdanov, Zh Eksper Teor Fiz, 53 (6), Dee 1967, 2099-2108 (in Russian).
14
629. On the possibility of resonance phenomena in the kinetics of
molecular gases. (USSR) Analyzing the viscosity and thermal conductivity in molecular gases like 0,. in perpendicular stationary and varying magnetic or electric fields, it is shown that for certain conditions the transfer and absorption coefficients are of a resonance nature. V D Borman et al, Zh Eksper Teor Fiz, 53 (6), Dee 1967, 2143-2153 (in Russian). 15. FLUID DYNAMICS
15 : 18 630. Transport properties of a nonequilibrium partially ionized gas in a magnetic field. (USA) A moditied Chapman-Enskog technique, developed for a partially ionized gas in an electric field, is generalized to include the effects of a magnetic field. The method allows the electron and heavy particle temperature to differ while requiring all species to have the same macroscopic velocity to zero order. Expressions are obtained for the transport properties of such a gas and a complete set of self-contained magnetohydrodynamic equations are presented. As an example, the
of publication,
and that at the
transport properties of a fully ionized gas, containing a single ion species, are evaluated using the cutoff Coulomb potential. In the limit of equal electron and ion temperatures, the results agree with previous work. R M Chmieleski and J H Ferziger, Phys Fluids, 10 (12), Dee 1967, 252&2530. 15 631. Condensation in a rapidly expanding metal vapour-inert gas mixture. (USA) An investigation of the condensation of metal vapour in an inert carrier gas accelerated through nozzles was carried out. The mixture used is primarily zinc vapour in helium gas. Particle size is determined by means of a shuttered sampling device combined with electron microscope techniques. The condensation onset point is determined by nozzle static pressure measurement. P M Sherman et al, Rep ARL-67-0071, A D-656708, April 1967, 92 pages (Sri Tech Aerospace Reps, 5 (22), 4024, N67--36986). 16. GASES AND SOLIDS
16 : 21 Cryosorption of hydrogen by 12-20°K carbon dioxide cryodeposits. See abstract number 666. 16 : 18 632. Photo-ionization method of determination of adsorbed molecule ionization potentials. (USSR) Ionization potentials of adsorbed molecules on ZnO were determined by the measurements of electrons emitted by the action of infrared monochromatic light beams on the sample. V M Bentsa et al,Pribory Tekh Eksper, 12 (6), Nov-Dee 1967,147-151 (in Russian). 16 633. Adsorption of helium on copper surfaces at 4.2”K.
(USSR) Helium was introduced into a system evacuated by a cryopump with a copper surface at 4.2”K and the pressure in the chamber was measured. At lo-” torr, about lo-’ cm3/cm2 of helium was adsorbed on the walls and at lO-6 torr, 3 x 10-Ocm3/cm2 of He (99.8 per cent of the introduced He) was adsorbed. N P Danilova and A I Shal’nikov, Pribory Tekh Eksper, 12 (6), NovDee 1967, 199 (in Russian). 16 634. Surface interactions of iodine vapour with tungsten.
(USA) The interactions of iodine vapour with a clean tungsten surface were studied by first absorbing the iodine on the tungsten ribbon and then thermally desorbing the adlayer. The composition of the desorption products was determined with a time-of-flight mass spectrometer. No evidence is found for the formation of surface compounds. Only iodine atoms and, at higher coverages, iodine molecules populate the surface. B McCarroll, J Chem Phys, 47 (12), 15 Dee 1967, 5077. 16 635. Surface structures and work function changes in oxygen adsorption on tungsten (100). (USA) It was found that 0, can interact in two distinct ways. At room temperature the adsorption occurs on top of an essentially undisturbed substrate. At higher temperatures 0 atoms can penetrate the surface and form reconstructed layers. Under various conditions several ordered structures are produced and the work function changes. P J Estrup and J Anderson, Rey NYO-3830-1, May 1967, 11 pages (Sci Tech Aerospace Reps, 5 (22), 4127, N67-37234). 293