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1060. Ionization constants in the Penning process
Classified abstracts 1050--1064 energies below 30 eV exhibit the same energy versus wave vector dependence as the emergence conditions for low-index, non-specular beams. S Anderson and B Kasemo, Phys Stat Sol (a), 4 (2), Feb 1971, 373-380. 16 1051. Adsorption of gases at low pressures on X-type zeolites. (Czechoslovakia) An experimental study of the sorption of air has been carried out at the temperature of its boiling point and at very low pressures on Xtype zeolites containing the monovalent cations Na + and Rb ÷ and the bivalent cation Ca ~+. The adsorption measurements were performed in a high-vacuum glass apparatus using a modification of the dynamic method. All samples were in powder form without bonding agent and were spread in the sorption element in a thin layer. It is found that in all cases the sorption obeys Henry's law. It has been shown that the kinetics of sorption and the limiting pressure are influenced by the ion exchange. While in the case of NaX under certain conditions, pressures of the order of 10-3 torr are attained, in the case of CaX, the final pressure is by one order of magnitude lower. As well as the equilibrium data, the kinetics of the adsorption also indicate that CaX is optimal for vacuum techniques, when air is the pumped gas. V Bosacek et al, Czech JPhys, B20 (8), 1970, 912-916. 16 1052. Surface oxidation phenomena on the faces of germanium single crystals. 4. On the mechanism of the oxidation process. (Hungary) Studies of the mechanism of oxygen sorption on faces of germanium single crystals support the assumption of an exchange mechanism being involved, mainly in the preferred position of the surface, through exchange between the surface lattice atoms of germanium and the oxygen atoms. It is supposed that these preferred positions are located on the peaks, edges and terraces found on the surface. J Kiraly, Mug Kemiai Folyoirat, 76 (5), 1970, 217-220 (in Hungarian). 16 1053. Adsorption of oxygen on nickel powders for cathodes of transmitter tubes. (USSR) Adsorption of oxygen on carbonyl and electrolytic nickel powders is investigated at pressures of 10-3 to 10-3 torr. It is found that the adsorption is composed of reversible and irreversible adsorptions, the portion of irreversible adsorption increasing with temperature rise. N N Kavtaradze et ai, Elektron Tekh Generator Modul Rentgen Prib, 3, 1969, 96-102 (in Russian).
18. GASEOUS ELECTRONICS 18 1054. Energy distribution in field emission from krypton covered tungsten. (USA) Work functions and energy distributions as functions of relative coverage were obtained for Kr absorbed on the (110), (100), (111) and (112) planes of a tungsten field emitter, from zero coverage to several monolayers. The data could be fitted by the Topping equation for depolarization, yielding polarizabilities in reasonable agreement with the atomic value if HCP monolayer densities were used, on all but the (110) plane where a higher value resulted. Energy distribution in the submonolayer range show no deviations from free-electron-like behaviour, except possibly on the (110) plane. On the (100) surface the Swanson anomaly found in the distribution from the clean surface decreases monotonically with K r coverage. Details of the procedure for depositing K r from a sublimation source and of the energy analyzer are given. C Lea and R Gomer, J Chem Phys, 54 (8), 15 April 1971, 3349-3359. 18 : 30 1055. The negative resistance region in the V-A characteristics of AI-AI~Os-Au systems. (Germany) In some cases a negative resistance region in the volt-ampere characteristics of A1-AI=O3-Au thin film systems is observed. It was found that the presence of the negative resistance region is associated with the occurrence of brightly lighting points in the image of the cathode in the emission electron microscope and this phenomenon occurs much more frequently when the material of the base electrode is of lower purity. The explanation of the negative resistance region is dealt with. L Frank, Phys Stat Sol (a), 4 (2), Feb 1971, K135-K138.
492
18 1056. Optically stimulated electron emission from LiF with thermal bleaching. (Germany) Optically stimulated exoelectron emission from LiF with thermal bleaching has been studied. The experimental results are discussed. W Kaul et al, Phys Star Sol(a), 4 (2), Feb 1971, KI01-K104. 18 1057. Evidence for F-hand in the electron emission spectrum of MgF2. (Germany) The photoemission study of MgF~ coloured by electron bombardment was performed. Experimental results are discussed. P Petrescu, Phys Stat Sol (a), 4 (2), Feb 1971, K91-K92. 18 1058. Slowing down of an intense electron beam in a dense plasma. (USSR) The slowing down of an intense monoenergetic electron beam of 20 A in a dense hydrogen plasma with concentration of l0 x3 cm -3 is studied experimentally. The longitudinal and total beam energy losses are measured. L P Zakatov and A G Piakhov, Zh Eksper Teor Fiz, 60 (2), Feb 1971, 588-593 (in Russian). 18 1059. Excitation of atoms in slow ion-atom collisions. (USSR) An experimental arrangement is described which was employed for studying the threshold behaviour of the optical spectral line excitation functions for cadmium and zinc atoms due to interaction between slow zinc ions and cadmium atoms. The experimental arrangement was evacuated by a pump with a speed of 250 litres/sec. The residual gas pressure was 2 × 10-7 torr, under working conditions 5× 10-7 torr. The absolute excitation cross sections for 13 spectral lines of the atoms are determined. O B Shpenik et al, Zh Eksper Teor Fiz, 60 (2), Feb 1971, 511-520 (in
Russian). 18 1060. Ionization constants in the Penning process. (USSR) The Penning effect of ionization of atoms in collisions with metastable atoms is investigated for the case when the ionization probability per collision is small. Some of the results obtained are confirmed experimentally. B M Smirnov, Zh Eksper Teor Fiz, 60 (1), Jan 1971, 66-68 (in Russian). 18 1061. Experimental investigation of efficient retardation of an ion beam in a plasma at ion-acoustic instability. (USSR) The interaction between an ion beam and plasma is studied experimentally under conditions when the beam excites ion-acoustic instability. The ion current was 2 mA, with 10-100 eV potassium ions and a working gas-argon pressure of 10-3 to 10-4 torr. It is found that when the beam velocities are comparable with the velocity of nonisothermal ion sound, efficient transfer of the ion beam energy to the plasma occurs. A G Borisenko and G S Kirichenko, Zh Eksper Teor Fiz, 60 (1), Jan 1971, 384-388 (in Russian). 18 1062. Schlierea method and its application to plasma diagnostics. (Czechoslovakia) The application of the Schlieren method for the measurement of electron, ion and atom density gradients in a plasma is described. V Hermoch, Czech J Phys, 1320 (8), 1970, 939-949. 18 1063. Field emission from high-ohmic n-type silicon. (Germany) Field emission from high-ohmic n-type silicon is investigated in a glass field-emission at pressures below 10-1° torr. Experimental results are discussed. H Neumann, Experim Techn Phys, 17 (4), 1969, 354-366 (in German). 18 : 32 1064. Cathodes used in the guns of linear accelerators. (USSR) The application possibilities of different cathodes in linear electron accelerators are investigated. The cathodes were examined in the pulsed mode at 80 kV, with pulse duration of 2 to 4 #sec and repetition rate of 50 to 250 sec-1. Oil diffusion pumps (without liquid nitrogen traps) and titanium pumps were used for evacuation of the test systems. The experiments showed that the L-cathode has low emission at 3 to 8 x 10-6 tort. Oxide cathodes in this pressure range with an enhanced temperature of 1000°C have the required emission but are rapidly poisoned and in the case of breakdown are impaired. The nickel matrix oxide cathode is resistant to breakdown but is rapidly
18. GASEOUS ELECTRONICS 18 1054. Energy distribution in field emission from krypton covered tungsten. (USA) Work functions and energy distributions as functions of relative coverage were obtained for Kr absorbed on the (110), (100), (111) and (112) planes of a tungsten field emitter, from zero coverage to several monolayers. The data could be fitted by the Topping equation for depolarization, yielding polarizabilities in reasonable agreement with the atomic value if HCP monolayer densities were used, on all but the (110) plane where a higher value resulted. Energy distribution in the submonolayer range show no deviations from free-electron-like behaviour, except possibly on the (110) plane. On the (100) surface the Swanson anomaly found in the distribution from the clean surface decreases monotonically with K r coverage. Details of the procedure for depositing K r from a sublimation source and of the energy analyzer are given. C Lea and R Gomer, J Chem Phys, 54 (8), 15 April 1971, 3349-3359. 18 : 30 1055. The negative resistance region in the V-A characteristics of AI-AI~Os-Au systems. (Germany) In some cases a negative resistance region in the volt-ampere characteristics of A1-AI=O3-Au thin film systems is observed. It was found that the presence of the negative resistance region is associated with the occurrence of brightly lighting points in the image of the cathode in the emission electron microscope and this phenomenon occurs much more frequently when the material of the base electrode is of lower purity. The explanation of the negative resistance region is dealt with. L Frank, Phys Stat Sol (a), 4 (2), Feb 1971, K135-K138.
492
18 1056. Optically stimulated electron emission from LiF with thermal bleaching. (Germany) Optically stimulated exoelectron emission from LiF with thermal bleaching has been studied. The experimental results are discussed. W Kaul et al, Phys Star Sol(a), 4 (2), Feb 1971, KI01-K104. 18 1057. Evidence for F-hand in the electron emission spectrum of MgF2. (Germany) The photoemission study of MgF~ coloured by electron bombardment was performed. Experimental results are discussed. P Petrescu, Phys Stat Sol (a), 4 (2), Feb 1971, K91-K92. 18 1058. Slowing down of an intense electron beam in a dense plasma. (USSR) The slowing down of an intense monoenergetic electron beam of 20 A in a dense hydrogen plasma with concentration of l0 x3 cm -3 is studied experimentally. The longitudinal and total beam energy losses are measured. L P Zakatov and A G Piakhov, Zh Eksper Teor Fiz, 60 (2), Feb 1971, 588-593 (in Russian). 18 1059. Excitation of atoms in slow ion-atom collisions. (USSR) An experimental arrangement is described which was employed for studying the threshold behaviour of the optical spectral line excitation functions for cadmium and zinc atoms due to interaction between slow zinc ions and cadmium atoms. The experimental arrangement was evacuated by a pump with a speed of 250 litres/sec. The residual gas pressure was 2 × 10-7 torr, under working conditions 5× 10-7 torr. The absolute excitation cross sections for 13 spectral lines of the atoms are determined. O B Shpenik et al, Zh Eksper Teor Fiz, 60 (2), Feb 1971, 511-520 (in
Russian). 18 1060. Ionization constants in the Penning process. (USSR) The Penning effect of ionization of atoms in collisions with metastable atoms is investigated for the case when the ionization probability per collision is small. Some of the results obtained are confirmed experimentally. B M Smirnov, Zh Eksper Teor Fiz, 60 (1), Jan 1971, 66-68 (in Russian). 18 1061. Experimental investigation of efficient retardation of an ion beam in a plasma at ion-acoustic instability. (USSR) The interaction between an ion beam and plasma is studied experimentally under conditions when the beam excites ion-acoustic instability. The ion current was 2 mA, with 10-100 eV potassium ions and a working gas-argon pressure of 10-3 to 10-4 torr. It is found that when the beam velocities are comparable with the velocity of nonisothermal ion sound, efficient transfer of the ion beam energy to the plasma occurs. A G Borisenko and G S Kirichenko, Zh Eksper Teor Fiz, 60 (1), Jan 1971, 384-388 (in Russian). 18 1062. Schlierea method and its application to plasma diagnostics. (Czechoslovakia) The application of the Schlieren method for the measurement of electron, ion and atom density gradients in a plasma is described. V Hermoch, Czech J Phys, 1320 (8), 1970, 939-949. 18 1063. Field emission from high-ohmic n-type silicon. (Germany) Field emission from high-ohmic n-type silicon is investigated in a glass field-emission at pressures below 10-1° torr. Experimental results are discussed. H Neumann, Experim Techn Phys, 17 (4), 1969, 354-366 (in German). 18 : 32 1064. Cathodes used in the guns of linear accelerators. (USSR) The application possibilities of different cathodes in linear electron accelerators are investigated. The cathodes were examined in the pulsed mode at 80 kV, with pulse duration of 2 to 4 #sec and repetition rate of 50 to 250 sec-1. Oil diffusion pumps (without liquid nitrogen traps) and titanium pumps were used for evacuation of the test systems. The experiments showed that the L-cathode has low emission at 3 to 8 x 10-6 tort. Oxide cathodes in this pressure range with an enhanced temperature of 1000°C have the required emission but are rapidly poisoned and in the case of breakdown are impaired. The nickel matrix oxide cathode is resistant to breakdown but is rapidly