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Test of the critical theory of electrical breakdown in vacuum
Classified
abstracts
1209-1222
uptake decreased when the filament temperature was increased. No dependence of sticking probability on pressure was found. R P H Gasser and R Thwaites, Vacuum, 17 (5), May 1967, 265-266. 17. THERMODYNAMICS 17 1209. Energy exchange in the interaction of atoms with the surface of an ideal crystal. (USSR) A method is discussed for computations of the energy exchange in the interactions of atoms with energy below 20 eV and the Einstein crystal lattice. Yu A Ryzhov and D S Strizhenov, Dokl Akad Nauk SSSR, 172 (6), 21st Feb 1967, 1309-131 18. GASEOUS
I (in Russian).
ELECTRONICS
18 1210. Test of the critical theory of electrical breakdown in vacuum. (USA) The critical-field theory of electrical breakdown in vacuum is shown to be applicable to all of the twelve metals and to the one alloy tested. In this theory the electric field at breakdown is predicted to be independent of gap spacing when the field considered is that existing in the neighbourhood of cathode field-emission sites. This field isenhanced with respect to the average gap field by a factor which can be calculated from measurements of the field emission current prior to breakdown. A vacuum tube has been employed for the experiment in which one electrode is movable and in which foils may be used for the electrode materials. The critical field for breakdown compares well with that calculated by others in the four metals for which previous data exist. P Kranjee and L Ruby, J Vat Sri Technol, 4 (2), March/April 1967, 94-96.
18 1211. Dissociative charge exchange of rare-gas ions with C,F, and (USA) C,F,. Dissociative charge exchange of rare-gas ions with C,F, and C,F, were studied with a single-stage mass spectrometer by operating the ion source in the Cermak-Herman mode. A charge-transfer mass spectrum was obtained for C,F, and C,F, with each rare-gas ion except Xe. Relative ion abundances were interpreted as showing the dissociation of C,F,+ and C3Fs+ as a function of their excitation energy. D Smith and L Kevan, J Chem Phys, 46 (5), 1st March 1967, 1586 1588. 18 1212. Hydrogen atom scattering: velocity dependence of total cross sections for scattering from rare gases, hydrogen and hydrocarbons. (USA) Thermal energy hydrogen atom beams are generated by dissociation of H, in a tungsten-tube furnace at -27OO”K, modulated by a mechanical chopper, and velocity selected by deflection in an inhomogeneous magnetic field. After passing through a scattering chamber containing the target gas, the atoms strike a platinum strip bolometer which functions as a catalytic recombination detector. Measurements of the velocity dependence of the total collision cross section in the range 3 to 11 x lo6 cm/set are given for scattering of H atoms from the rare gases, H,, CH,, C,H,, CIH,, C2HB, and C(CH,),. The results show that throughout this range attractive rB interactions are still predominant for Xe, C,H, and C(CH,),, whereas repulsive interactions are predominant for most of the other gases. M A D Fluendy et al, J Chem Phys, 46 (6), 15th March 1967, 21722181. 1213. Ionization cross sections of the elements calculated square radii of atomic orbitals. (USA)
18 from mean-
Relative ionization cross sections for single ionization by electron impact on free gaseous atoms have been calculated by using a summation of the mean-square orbital radii of outer electrons. Hartree-Fock calculations of orbital wave functions have been carried out for all elements. Mean-square-radii of atomic orbitals from the Hartree-Fock calculations were corrected approximately for relativistic effects. Ionization cross sections were normalized at argon and compared with experimental data. J B Mann, J Chem Phys, 46 (5), 1st March 1967, 1646-165 I. 420
1214. Synthesis of ammonia secondary ion-ion emission.
on iron, as investigated (USSR)
18 : 38 by the method of
Using the secondary ion-ion emission method, the mechanism of the catalytic reaction between N, and H, on Fe catalyst, at 10m4torr and at temperatures of 20 to SWC, was investigated. V V Shvachko et al, Dokl Akad Nauk SSSR, 172 (6), 21sr Feb 1967, 1353-1356 (in Russian). 18 1215. Energy spectrum of electron emission from a single KC1 crystal bombarded by helium ions. (USSR) The ion-electron emission from a KC1 single crystal was investigated with perpendicular bombardment of the (100) face by He ions, of energy 20 to 400 eV. The minimal energy for driving an electron from the solid KC1 was found to be 8 eV. The influence of field emission on the observed electron energy distribution is discussed. A I Kondrashev and N N Petrov, Dokl Akad Nauk SSSR, 173 (I), 1st March 1967, 67-69 (in Russian). 1216. Adsorption and electron emission of potassium tungsten single crystal. (USSR)
18 films on faces of
Using a field-emission microscope, the energy of adsorption of potassium on the (100), (1 lo), (111) and (112) faces of tungsten single crystal was found to be 1.9 &.l eV. The minimal work function of potassium films on tungsten was determined as 1.75 f.15 eV. A P Ovchinnikov, Russian).
Fiz
Tverd
Tela,
9 (2), Feb 1967,
628-633
(in 18
1217. Temperature dependence halide single crystals. (USSR)
of ion-electron
emission from alkali
The ion-electron emission from (100) faces of KC1 and KBr single crystals, bombarded by K+ ions with energies up to 8 keV at temperatures 100 to 300’%, was investigated. It was found that the temperature dependence of the emission is caused by electrons losing energy in the form of phonons. I A Abroyan et al, Fiz Tverd Tela, 9 (2), Feb 1967, 667-669 (in Russian). 18 1218. Inelastic scattering of 0.2 to 0.8 keV electrons on Be and Pb for large incident angle of primary beam. (USSR)
Some anomalies were observed in the measured inelastic scattering coefficient of low energy electrons on beryllium and lead. I M Bronshteyn and V A Dolinin, Fiz Tverd T&a, 9 (2), Feb 1967, 683-684
(in Russian).
18 1219. Diagnostics
of a low temperature
caesium plasma.
(USSR)
Using the Langmuir probe, the electron density and potential distributions in a diode with a hot cathode and Cs vapour atmosphere at pressures of 1O-2 to 1 torr were measured. Conditions for initiating the low-voltage arc discharge were also investigated. N V Volkov et al, Zh Tekh Fiz, 37 (3), March 1967, 504-512 (in Russian).
18 1220. Investigation of the time excited argon atoms. (USSR)
correlation
of photons
emitted
by
Argon atoms at a pressure of 10m3 torr were excited by electron impact and an average emission of 2.75 photons per collision, which is higher than the theoretical value, was obtained. Yu F Skachkov, Zh Eksper Teor Fiz, 52 (3), March 1967, 637-642 (in Russian).
18 1221. Resonance magnetic wave.
ionization (USSR)
of atoms in the field of a strong electro-
A theoretical analysis was carried out on the ionization of atoms when the separation between the energy levels in the atom is a multiple of the light frequency of the laser beam. L P Kotova and M V Terent’ev, Zh Eksper 1967, 732-741 (in Russian).
Teor Fiz, 52 (31, March
18 : 31 1222. Thermoelectric emission of photoeathodes. (Czechoslovakia) After a general introduction to the physical aspects of the problem, a measuring technique using an improved photomultiplier is described. Temperature dependence factors of 1 x 10m3 to 4 x lo-” eV/“C for the range 20 to 70°C were found for the work functions of several conventional photocathode materials. The effects of partial
abstracts
1209-1222
uptake decreased when the filament temperature was increased. No dependence of sticking probability on pressure was found. R P H Gasser and R Thwaites, Vacuum, 17 (5), May 1967, 265-266. 17. THERMODYNAMICS 17 1209. Energy exchange in the interaction of atoms with the surface of an ideal crystal. (USSR) A method is discussed for computations of the energy exchange in the interactions of atoms with energy below 20 eV and the Einstein crystal lattice. Yu A Ryzhov and D S Strizhenov, Dokl Akad Nauk SSSR, 172 (6), 21st Feb 1967, 1309-131 18. GASEOUS
I (in Russian).
ELECTRONICS
18 1210. Test of the critical theory of electrical breakdown in vacuum. (USA) The critical-field theory of electrical breakdown in vacuum is shown to be applicable to all of the twelve metals and to the one alloy tested. In this theory the electric field at breakdown is predicted to be independent of gap spacing when the field considered is that existing in the neighbourhood of cathode field-emission sites. This field isenhanced with respect to the average gap field by a factor which can be calculated from measurements of the field emission current prior to breakdown. A vacuum tube has been employed for the experiment in which one electrode is movable and in which foils may be used for the electrode materials. The critical field for breakdown compares well with that calculated by others in the four metals for which previous data exist. P Kranjee and L Ruby, J Vat Sri Technol, 4 (2), March/April 1967, 94-96.
18 1211. Dissociative charge exchange of rare-gas ions with C,F, and (USA) C,F,. Dissociative charge exchange of rare-gas ions with C,F, and C,F, were studied with a single-stage mass spectrometer by operating the ion source in the Cermak-Herman mode. A charge-transfer mass spectrum was obtained for C,F, and C,F, with each rare-gas ion except Xe. Relative ion abundances were interpreted as showing the dissociation of C,F,+ and C3Fs+ as a function of their excitation energy. D Smith and L Kevan, J Chem Phys, 46 (5), 1st March 1967, 1586 1588. 18 1212. Hydrogen atom scattering: velocity dependence of total cross sections for scattering from rare gases, hydrogen and hydrocarbons. (USA) Thermal energy hydrogen atom beams are generated by dissociation of H, in a tungsten-tube furnace at -27OO”K, modulated by a mechanical chopper, and velocity selected by deflection in an inhomogeneous magnetic field. After passing through a scattering chamber containing the target gas, the atoms strike a platinum strip bolometer which functions as a catalytic recombination detector. Measurements of the velocity dependence of the total collision cross section in the range 3 to 11 x lo6 cm/set are given for scattering of H atoms from the rare gases, H,, CH,, C,H,, CIH,, C2HB, and C(CH,),. The results show that throughout this range attractive rB interactions are still predominant for Xe, C,H, and C(CH,),, whereas repulsive interactions are predominant for most of the other gases. M A D Fluendy et al, J Chem Phys, 46 (6), 15th March 1967, 21722181. 1213. Ionization cross sections of the elements calculated square radii of atomic orbitals. (USA)
18 from mean-
Relative ionization cross sections for single ionization by electron impact on free gaseous atoms have been calculated by using a summation of the mean-square orbital radii of outer electrons. Hartree-Fock calculations of orbital wave functions have been carried out for all elements. Mean-square-radii of atomic orbitals from the Hartree-Fock calculations were corrected approximately for relativistic effects. Ionization cross sections were normalized at argon and compared with experimental data. J B Mann, J Chem Phys, 46 (5), 1st March 1967, 1646-165 I. 420
1214. Synthesis of ammonia secondary ion-ion emission.
on iron, as investigated (USSR)
18 : 38 by the method of
Using the secondary ion-ion emission method, the mechanism of the catalytic reaction between N, and H, on Fe catalyst, at 10m4torr and at temperatures of 20 to SWC, was investigated. V V Shvachko et al, Dokl Akad Nauk SSSR, 172 (6), 21sr Feb 1967, 1353-1356 (in Russian). 18 1215. Energy spectrum of electron emission from a single KC1 crystal bombarded by helium ions. (USSR) The ion-electron emission from a KC1 single crystal was investigated with perpendicular bombardment of the (100) face by He ions, of energy 20 to 400 eV. The minimal energy for driving an electron from the solid KC1 was found to be 8 eV. The influence of field emission on the observed electron energy distribution is discussed. A I Kondrashev and N N Petrov, Dokl Akad Nauk SSSR, 173 (I), 1st March 1967, 67-69 (in Russian). 1216. Adsorption and electron emission of potassium tungsten single crystal. (USSR)
18 films on faces of
Using a field-emission microscope, the energy of adsorption of potassium on the (100), (1 lo), (111) and (112) faces of tungsten single crystal was found to be 1.9 &.l eV. The minimal work function of potassium films on tungsten was determined as 1.75 f.15 eV. A P Ovchinnikov, Russian).
Fiz
Tverd
Tela,
9 (2), Feb 1967,
628-633
(in 18
1217. Temperature dependence halide single crystals. (USSR)
of ion-electron
emission from alkali
The ion-electron emission from (100) faces of KC1 and KBr single crystals, bombarded by K+ ions with energies up to 8 keV at temperatures 100 to 300’%, was investigated. It was found that the temperature dependence of the emission is caused by electrons losing energy in the form of phonons. I A Abroyan et al, Fiz Tverd Tela, 9 (2), Feb 1967, 667-669 (in Russian). 18 1218. Inelastic scattering of 0.2 to 0.8 keV electrons on Be and Pb for large incident angle of primary beam. (USSR)
Some anomalies were observed in the measured inelastic scattering coefficient of low energy electrons on beryllium and lead. I M Bronshteyn and V A Dolinin, Fiz Tverd T&a, 9 (2), Feb 1967, 683-684
(in Russian).
18 1219. Diagnostics
of a low temperature
caesium plasma.
(USSR)
Using the Langmuir probe, the electron density and potential distributions in a diode with a hot cathode and Cs vapour atmosphere at pressures of 1O-2 to 1 torr were measured. Conditions for initiating the low-voltage arc discharge were also investigated. N V Volkov et al, Zh Tekh Fiz, 37 (3), March 1967, 504-512 (in Russian).
18 1220. Investigation of the time excited argon atoms. (USSR)
correlation
of photons
emitted
by
Argon atoms at a pressure of 10m3 torr were excited by electron impact and an average emission of 2.75 photons per collision, which is higher than the theoretical value, was obtained. Yu F Skachkov, Zh Eksper Teor Fiz, 52 (3), March 1967, 637-642 (in Russian).
18 1221. Resonance magnetic wave.
ionization (USSR)
of atoms in the field of a strong electro-
A theoretical analysis was carried out on the ionization of atoms when the separation between the energy levels in the atom is a multiple of the light frequency of the laser beam. L P Kotova and M V Terent’ev, Zh Eksper 1967, 732-741 (in Russian).
Teor Fiz, 52 (31, March
18 : 31 1222. Thermoelectric emission of photoeathodes. (Czechoslovakia) After a general introduction to the physical aspects of the problem, a measuring technique using an improved photomultiplier is described. Temperature dependence factors of 1 x 10m3 to 4 x lo-” eV/“C for the range 20 to 70°C were found for the work functions of several conventional photocathode materials. The effects of partial