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1053. Thermionic properties of metallic alloys
Classified abstracts 1053-1066 deviations from ideal behaviour have on the efficiency of adsorption in charcoal beds. Experimental measurements were made of the adsorption and desorption of K.r85 in an air carrier in charcoal beds cooled with dry ice. D W Uoderhill, Rep NY0-841-8, April 1967, 146 pages (Sci Tech Aerospace Reps, 6 (4), 467, N68-13364).
18. GASEOUS ELECTRONICS 18 : 16 Study of the structure and work function of platinum layers on tungsten and caesium adsorption on the layers. See abstract number 1047. 18 : 16 Caesium behaviour on the faces of large single crystals of tungsten. See abstract number 1049. 18 : 21 Secondary electron emission from diffusion pump oils and a vacuum grease. See abstract number 1080. 18 : 41 1053. Thermionic properties of metallic alloys. (USSR) This review article, summarizes the literature values of the work function and its temperature dependence, covering 40 two-component, metallic alloys and solutions, 19 two-component metallic compositions and 29 multicomponent alloys including alloys with metallic borides, carbides and oxides. Applications as cathode materials and emission properties are discussed. T L Matskevich, Zh Tekh Fiz, 38 (3), March 1968, 401-417 (in
Russian). 18 1054. Solution of kinetic equations for a thermionic converter in the ignited state. (USSR) Equations are solved for the electron distribution functions in a thermionic converter, taking into account both elastic and nonelastic electron--atom coUissions of the first and second order and ionization. E B Sonin, Zh Tekh Fiz, 38 (3), March 1968, 434-441 (in Russian). 18 1055. Application of Galerkin's method to some problems of positive column theory. (USSR) An expression is derived relating the coefficient of direct ionization, step ionization and volume recombination to the ambipolar diffusion coefficient, the column radius and the electron density on the axis and near to the walls. L E Belousova, Zh Tekh Fiz, 38 (3), March 1968, 457-461 (ht Russian). 18 1056. Investigation of the external photoelectric effect in aluminium single crystals. (USSR) From measurements of the photocmission from pure aluminium single crystals excited by light of 2537 /~ wavelength, work function values of 3.38 eV for the (100) face and 3.11 eV for the (111) face were obtained. (Poland) B Seroczynska-Wojas, Fiz Tverd Tela, 10 (3), March 1968, 693-702
(in Russian). 18 1057. Emission characteristics of niobium single crystal faces. (USSR) Richardson lines were measured for niobium single crystal faces and the following work functions were obtained: 4.80 eV for the (110) face, 3.95 eV for the (100), 3.88 eV for the (111) and 3.70 eV for the (116) face for the range 1400 to 2000°K. For the (111) and (116) faces the calculated Richardson constant, A0, strongly differed from the theoretical value and this effect is discussed. O D Protopopov and I V Strigushcbenko, Fiz Tverd Tela, 10 (3), March 1968, 943-945 (in Russian). 18 1058. Ion-electron emission of NaCl and KCI single crystals under different incidence angles of slow inert gas ions. (USSR) The (001) faces of NaCI and KC1 single crystals were bombarded by positive He and Ne ions with energies of 70 to 700 eV, and the ion-electron emission coefficient was measured for incidence angles of 0 to 60 °. Above 150 eV, the dependence of the coefficient on the angle is nonmonotonic with the lowest emission for the zero incidence angle. N N Petrov et al, Fiz Tverd Tela, 10 (4), April 1968, 1053-1057
(in Russian). 488
18 1059. Potential and kinetic emission of electrons from (110) and (111) faces of molybdenum crystals. (USSR) Carefully cleaned (110) and (111) faces of molybdenum single crystals were bombarded by He and Ar atoms and ions, and potential and kinetic emission characteristics were measured. No direct correlation between changes of the work function of the faces and differences of the emission was observed. U A Arifov et al, Fiz Tverd Tela, 10 (4), April 1968, 1166-1172
(in Russian). 1060. Investigation of electron densities in the decayed plasma of a pulse discharge. (USSR) The electron concentration was measured during the decay of a pulse discharge plasma, by means of an optical interferometric method. The plasma was excited by discharging 40/xF charged 3.5 kV in He 3 and Ar at a pressure of 0.6 to 3 tort. V V Tatarinov et al, Izv VUZ Fiz, 11 (3), 1968, 131-133 (in Russian). 18 1061. Investigation of surface radiation damage by the exoelectron emission method. (USSR) Exoelectron emission was measured from A1203 samples at 300°K under vacuum of 10 7 tort, to investigate surface damage and the influence of x-ray radiation on chemisorption processes. D I Baazov et al, Izv VUZ Fiz, 11 (3), 1968, 150-152 (in Russian). 18 1062. Growth of ionization currents in carbon tetrafluoride and hexafluoroethane. (Great Britain) Values of the ionization coefficient a and attachment coefficient/~ have been obtained in carbon tetrafluoride (CF4) and hexafluoroethane (C~Fe) at 20°C using the modified Townsend method. In CF 4 the reduced field E/p was varied from 40 to 90 v cm 1 torr-~ and the reduced coefficients a/P and # / p were found to be independent of pressure from 5 to 20 torr. S E Bozin and C C Goodyear, Brit J Appl Phys, Set 2, l (3), 1968, 327-334. 18 1063. Transient response of the Langmuir probe at low pressures. (Great Britain) Quantitative measurements have been made of the spike in the positive-ion current which accompanies the application of a negative pulse to a Langmuir probe. The measurements have been performed over a wide range of applied voltage (1-400 V) and ion density (l(P--10 ~ ions/cm3), and at a pressure (.01 torr) where a collisionless model of plasma sheath may be expected to apply. The implications of these results to swept-probe measurements have been investigated directly by sweeping a double probe at various sweep rates in the same plasma. It is found, as expected, that above a certain sweep rate the probe characteristics are distorted. P R Stay and J R Greig, BritJ ApplPhys, Ser 2, 1 (3), 1968, 351-359. 18 : 33 1064. Vacuum insulation between very cold niobium electrodes. (Great Britain) As the temperature of a parallel-plate niobium electrode system in vacuum is reduced from room temperature to 4.2°K the pre-breakdown current is greatly reduced and the breakdown voltage significantly increased. No change in current or voltage was detected at the onset of superconductivity. J S T Looms et al, Brit J Appl Phys, Set, 2 1 (3), 1968, 377-379. 18 1065. Discharge in gas desorbed from the anode in a crossed fields annular ion source. (Holland) The operation of an annular ion source with crossed electric and magnetic fields, in which the anode is made of titanium, is compared with the operation of the same source with a copper anode. When the titanium anode is loaded with hydrogen, the discharge can develop in the gas coming from the titanium. The gas concentration is maximum in the discharge region near the anode and the gas efficiency of the source is increased by a factor of two. (France) R Becherer et al, Nucl Instrum Methods, 59 (2), 1968, 329-332. 18 1066. Non-Maxwellian form of the electron velocity distribution in nitrogen plasmas. (USA) Changes in the form of the electron velocity distribution with time in the active discharge and in the afterglow of a low-energy nitrogen plasma immersed in a magnetic field, were investigated. The vacuum
18. GASEOUS ELECTRONICS 18 : 16 Study of the structure and work function of platinum layers on tungsten and caesium adsorption on the layers. See abstract number 1047. 18 : 16 Caesium behaviour on the faces of large single crystals of tungsten. See abstract number 1049. 18 : 21 Secondary electron emission from diffusion pump oils and a vacuum grease. See abstract number 1080. 18 : 41 1053. Thermionic properties of metallic alloys. (USSR) This review article, summarizes the literature values of the work function and its temperature dependence, covering 40 two-component, metallic alloys and solutions, 19 two-component metallic compositions and 29 multicomponent alloys including alloys with metallic borides, carbides and oxides. Applications as cathode materials and emission properties are discussed. T L Matskevich, Zh Tekh Fiz, 38 (3), March 1968, 401-417 (in
Russian). 18 1054. Solution of kinetic equations for a thermionic converter in the ignited state. (USSR) Equations are solved for the electron distribution functions in a thermionic converter, taking into account both elastic and nonelastic electron--atom coUissions of the first and second order and ionization. E B Sonin, Zh Tekh Fiz, 38 (3), March 1968, 434-441 (in Russian). 18 1055. Application of Galerkin's method to some problems of positive column theory. (USSR) An expression is derived relating the coefficient of direct ionization, step ionization and volume recombination to the ambipolar diffusion coefficient, the column radius and the electron density on the axis and near to the walls. L E Belousova, Zh Tekh Fiz, 38 (3), March 1968, 457-461 (ht Russian). 18 1056. Investigation of the external photoelectric effect in aluminium single crystals. (USSR) From measurements of the photocmission from pure aluminium single crystals excited by light of 2537 /~ wavelength, work function values of 3.38 eV for the (100) face and 3.11 eV for the (111) face were obtained. (Poland) B Seroczynska-Wojas, Fiz Tverd Tela, 10 (3), March 1968, 693-702
(in Russian). 18 1057. Emission characteristics of niobium single crystal faces. (USSR) Richardson lines were measured for niobium single crystal faces and the following work functions were obtained: 4.80 eV for the (110) face, 3.95 eV for the (100), 3.88 eV for the (111) and 3.70 eV for the (116) face for the range 1400 to 2000°K. For the (111) and (116) faces the calculated Richardson constant, A0, strongly differed from the theoretical value and this effect is discussed. O D Protopopov and I V Strigushcbenko, Fiz Tverd Tela, 10 (3), March 1968, 943-945 (in Russian). 18 1058. Ion-electron emission of NaCl and KCI single crystals under different incidence angles of slow inert gas ions. (USSR) The (001) faces of NaCI and KC1 single crystals were bombarded by positive He and Ne ions with energies of 70 to 700 eV, and the ion-electron emission coefficient was measured for incidence angles of 0 to 60 °. Above 150 eV, the dependence of the coefficient on the angle is nonmonotonic with the lowest emission for the zero incidence angle. N N Petrov et al, Fiz Tverd Tela, 10 (4), April 1968, 1053-1057
(in Russian). 488
18 1059. Potential and kinetic emission of electrons from (110) and (111) faces of molybdenum crystals. (USSR) Carefully cleaned (110) and (111) faces of molybdenum single crystals were bombarded by He and Ar atoms and ions, and potential and kinetic emission characteristics were measured. No direct correlation between changes of the work function of the faces and differences of the emission was observed. U A Arifov et al, Fiz Tverd Tela, 10 (4), April 1968, 1166-1172
(in Russian). 1060. Investigation of electron densities in the decayed plasma of a pulse discharge. (USSR) The electron concentration was measured during the decay of a pulse discharge plasma, by means of an optical interferometric method. The plasma was excited by discharging 40/xF charged 3.5 kV in He 3 and Ar at a pressure of 0.6 to 3 tort. V V Tatarinov et al, Izv VUZ Fiz, 11 (3), 1968, 131-133 (in Russian). 18 1061. Investigation of surface radiation damage by the exoelectron emission method. (USSR) Exoelectron emission was measured from A1203 samples at 300°K under vacuum of 10 7 tort, to investigate surface damage and the influence of x-ray radiation on chemisorption processes. D I Baazov et al, Izv VUZ Fiz, 11 (3), 1968, 150-152 (in Russian). 18 1062. Growth of ionization currents in carbon tetrafluoride and hexafluoroethane. (Great Britain) Values of the ionization coefficient a and attachment coefficient/~ have been obtained in carbon tetrafluoride (CF4) and hexafluoroethane (C~Fe) at 20°C using the modified Townsend method. In CF 4 the reduced field E/p was varied from 40 to 90 v cm 1 torr-~ and the reduced coefficients a/P and # / p were found to be independent of pressure from 5 to 20 torr. S E Bozin and C C Goodyear, Brit J Appl Phys, Set 2, l (3), 1968, 327-334. 18 1063. Transient response of the Langmuir probe at low pressures. (Great Britain) Quantitative measurements have been made of the spike in the positive-ion current which accompanies the application of a negative pulse to a Langmuir probe. The measurements have been performed over a wide range of applied voltage (1-400 V) and ion density (l(P--10 ~ ions/cm3), and at a pressure (.01 torr) where a collisionless model of plasma sheath may be expected to apply. The implications of these results to swept-probe measurements have been investigated directly by sweeping a double probe at various sweep rates in the same plasma. It is found, as expected, that above a certain sweep rate the probe characteristics are distorted. P R Stay and J R Greig, BritJ ApplPhys, Ser 2, 1 (3), 1968, 351-359. 18 : 33 1064. Vacuum insulation between very cold niobium electrodes. (Great Britain) As the temperature of a parallel-plate niobium electrode system in vacuum is reduced from room temperature to 4.2°K the pre-breakdown current is greatly reduced and the breakdown voltage significantly increased. No change in current or voltage was detected at the onset of superconductivity. J S T Looms et al, Brit J Appl Phys, Set, 2 1 (3), 1968, 377-379. 18 1065. Discharge in gas desorbed from the anode in a crossed fields annular ion source. (Holland) The operation of an annular ion source with crossed electric and magnetic fields, in which the anode is made of titanium, is compared with the operation of the same source with a copper anode. When the titanium anode is loaded with hydrogen, the discharge can develop in the gas coming from the titanium. The gas concentration is maximum in the discharge region near the anode and the gas efficiency of the source is increased by a factor of two. (France) R Becherer et al, Nucl Instrum Methods, 59 (2), 1968, 329-332. 18 1066. Non-Maxwellian form of the electron velocity distribution in nitrogen plasmas. (USA) Changes in the form of the electron velocity distribution with time in the active discharge and in the afterglow of a low-energy nitrogen plasma immersed in a magnetic field, were investigated. The vacuum