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830. Pre-breakdown ionization in molecular nitrogen in EB fields
Classified abstracts 826-873 Classified abstracts 826-834 on this page
Abstracting editor's note The label immediatelyfollowing the title of each item denotes country or origin of publication, and that at the end of each abstract indicates country of origin of work (where known).
I. General vacuum science and engineering 11. Production of low pressures 11:33 826. Ultra-high vacuum techniques. (Germany) Methods of achieving very low pressures are surveyed. The importance of surface phenomena is stressed, and features associated with adsorption and desorption of residual gases in relation to electronic properties are discussed. (Germany) L Jung, Tech Mitt RFZ, 9 (1), March 1965, 33-43, (in German).
12. Measurement of low pressures 12 827. The case for replacing the torr by the millibar as a unit of pressure. (USA) B J Nicholson, J Vacuum Sci Technol, 2 (3), May-June 1965,
161-162. 16. Gases and solids 16 : 21
828. The sorption of N2, Ha and D2 on titanium films at 20°C and -- 190 °C. (Great Britain) The sorption rate and capacity of evaporated Ti-films (10 to 350A. thick) deposited at two substrate temperatures (20°C, --190°C) have been measured as a function of time for N2, Ha and D~ at film temperatures of 20 °C and --190 °C. Measurements were made with a constant gas pressure of 5 × 10 -s tort. For N~, sorption was irreversible at a film temperature of 20 °C but reversible at --190 °C. The gas capacity of a film 170A- thick deposited and measured at --190°C was equivalent to 10 monomolecular layers. The initial sorption speed of such a film was 2.7 l.sec-~cm-2 giving a sticking coefficient of 0.22. Sorption of H2 by Ti-films at --190°C was reversible. The gas capacity of films of about 40~ thickness deposited and measured at --190°C was equal to 4 monolayers. The initial sorption speed rose from about 0.3 l.sec-lcm-~ for 20°C films to 10 l.sec-lcm-z for --190°C films. Results for Dz resemble those for H~ and gave an initial sorption speed of between 4 and 7 l.sec-Xcm-2. When low temperature deposits were heated to 20°C under ultra-high vacuum after gas saturation, the degassed films had similar sorption characteristics to films deposited and measured at 20°C. This effect was attributed to the reversibility of the sorption and the removal of structural defects in the surfaces of the film crystallites. L Elsworth et al, Vacuum, 15 (7), July 1965, 337-345.
17. T h e r m o d y n a m i c s 17 : 37 : 53 Thermodynamic and kinetic aspects of vacuum degassing. See abstract number 868.
the pressure range 10 -7 to 10 -4 torr. The ion density under these: conditions is calculated analytically and numerically; the density of slow electrons is also discussed. H Hartuagel, lnternat J Electronics, 18 (3), May 1965, 431-448. 18: 830. Pre-breakdown ionization in molecular nitrogen in EB fields.
(Australia) Pre-breakdown ionization measurements in molecular nitrogen are examined to establish whether the influence of a traverse magnetic field is equivalent to an increase in the gas pressure from p to Pe = p(1 q- ~oz/v2)½, where oJ is the electron cyclotron frequency, and v is a constant, effective, electron-molecule collision frequency. When the value of E/pe lies within the range 150 < E/p~ < 250V cm -1 torr -x, v has a constant value equal to 8.3 × 109 psec -1, but when, E/pe < 150, v/p must decrease with decreasing E/pe for satisfactory agreement to be maintained. The possibility of extending the concept to account for the changes in secondary ionization and the: breakdown potential in nitrogen are also discussed. (Australia) F T Bagnall and S C Haydon, Aus JPhys, 18, June 1965, 227. 18: 831. Transport coefficients for low energy electrons in crossed electric and magnetic fields. (Australia) Experimental results are given for the ratio Wx/W~ of transverse t o longitudinal drift velocity for electron swarms in nitrogen moving: in crossed electric and magnetic fields. The results, obtained by Huxley's method, cover the range 0.04 < E/p < 8.0 V cm -x torr -x at 293 °K. The apparatus and experimental procedures which have: been developed permit accurate measurements to be made so that significant tests of the method have been possible over wide ranges. of the experimental parameters. Information concerning the variation of the momentum transfer cross-section with electron energy, and concerning the energy distribution function, can be obtained by comparing a quantity WM = (E/B)(Wx/W~) with the true drift velocity IV. The results of this comparison are discussed in relatior~ to recent theoretical analyses. (Australia) R L Jory, Aus JPhys, 18, June 1965, 237. 18:4ff 832. A deviation from Paschen's law in mercury vaponr. (Great
Britain) While investigating the electrical properties of mercury at low pressures, a linear relationship was found between the minimum breakdown potential and the electrode separation. G D N Overton, et al, Brit J Appl Phys, 16 (5), May 1965, 731-732. 18:40' 833. Primary ionization coefficients in mercury vapour at low pressures using a pool cathode. (Great Britain) The Townsend ionization coefficients in mercury vapour, using a mercury pool cathode under uniform field conditions, are presented and compared with previously obtained values. D E Davies and D Smith, Brit J Appl Phys, 16 (5), May 1965,
697-701. 19. Radiation
18. Gaseous electronics 18 : 33 829. Ion distribution in the drift region of tubular electron beams.
(Great Britain) In the drift region of a tubular electron beam, ions are focussed on the centre of the beam by the space charge force of the beam electrons, the ions being formed by electron-molecule collisions in
19 : 51 834. Test of the constancy of the velocity of electromagnetic radiation in high vacuum. (USA) An experiment with coherent light reflected from a moving mirror was performed at a pressure less than 10 -e torr, the result being consistent with the constant velocity of light. P Beckmann and P Mandics, J Res Nat Bur Stand, 69D (4), April
1965, 623-628. 521
Abstracting editor's note The label immediatelyfollowing the title of each item denotes country or origin of publication, and that at the end of each abstract indicates country of origin of work (where known).
I. General vacuum science and engineering 11. Production of low pressures 11:33 826. Ultra-high vacuum techniques. (Germany) Methods of achieving very low pressures are surveyed. The importance of surface phenomena is stressed, and features associated with adsorption and desorption of residual gases in relation to electronic properties are discussed. (Germany) L Jung, Tech Mitt RFZ, 9 (1), March 1965, 33-43, (in German).
12. Measurement of low pressures 12 827. The case for replacing the torr by the millibar as a unit of pressure. (USA) B J Nicholson, J Vacuum Sci Technol, 2 (3), May-June 1965,
161-162. 16. Gases and solids 16 : 21
828. The sorption of N2, Ha and D2 on titanium films at 20°C and -- 190 °C. (Great Britain) The sorption rate and capacity of evaporated Ti-films (10 to 350A. thick) deposited at two substrate temperatures (20°C, --190°C) have been measured as a function of time for N2, Ha and D~ at film temperatures of 20 °C and --190 °C. Measurements were made with a constant gas pressure of 5 × 10 -s tort. For N~, sorption was irreversible at a film temperature of 20 °C but reversible at --190 °C. The gas capacity of a film 170A- thick deposited and measured at --190°C was equivalent to 10 monomolecular layers. The initial sorption speed of such a film was 2.7 l.sec-~cm-2 giving a sticking coefficient of 0.22. Sorption of H2 by Ti-films at --190°C was reversible. The gas capacity of films of about 40~ thickness deposited and measured at --190°C was equal to 4 monolayers. The initial sorption speed rose from about 0.3 l.sec-lcm-~ for 20°C films to 10 l.sec-lcm-z for --190°C films. Results for Dz resemble those for H~ and gave an initial sorption speed of between 4 and 7 l.sec-Xcm-2. When low temperature deposits were heated to 20°C under ultra-high vacuum after gas saturation, the degassed films had similar sorption characteristics to films deposited and measured at 20°C. This effect was attributed to the reversibility of the sorption and the removal of structural defects in the surfaces of the film crystallites. L Elsworth et al, Vacuum, 15 (7), July 1965, 337-345.
17. T h e r m o d y n a m i c s 17 : 37 : 53 Thermodynamic and kinetic aspects of vacuum degassing. See abstract number 868.
the pressure range 10 -7 to 10 -4 torr. The ion density under these: conditions is calculated analytically and numerically; the density of slow electrons is also discussed. H Hartuagel, lnternat J Electronics, 18 (3), May 1965, 431-448. 18: 830. Pre-breakdown ionization in molecular nitrogen in EB fields.
(Australia) Pre-breakdown ionization measurements in molecular nitrogen are examined to establish whether the influence of a traverse magnetic field is equivalent to an increase in the gas pressure from p to Pe = p(1 q- ~oz/v2)½, where oJ is the electron cyclotron frequency, and v is a constant, effective, electron-molecule collision frequency. When the value of E/pe lies within the range 150 < E/p~ < 250V cm -1 torr -x, v has a constant value equal to 8.3 × 109 psec -1, but when, E/pe < 150, v/p must decrease with decreasing E/pe for satisfactory agreement to be maintained. The possibility of extending the concept to account for the changes in secondary ionization and the: breakdown potential in nitrogen are also discussed. (Australia) F T Bagnall and S C Haydon, Aus JPhys, 18, June 1965, 227. 18: 831. Transport coefficients for low energy electrons in crossed electric and magnetic fields. (Australia) Experimental results are given for the ratio Wx/W~ of transverse t o longitudinal drift velocity for electron swarms in nitrogen moving: in crossed electric and magnetic fields. The results, obtained by Huxley's method, cover the range 0.04 < E/p < 8.0 V cm -x torr -x at 293 °K. The apparatus and experimental procedures which have: been developed permit accurate measurements to be made so that significant tests of the method have been possible over wide ranges. of the experimental parameters. Information concerning the variation of the momentum transfer cross-section with electron energy, and concerning the energy distribution function, can be obtained by comparing a quantity WM = (E/B)(Wx/W~) with the true drift velocity IV. The results of this comparison are discussed in relatior~ to recent theoretical analyses. (Australia) R L Jory, Aus JPhys, 18, June 1965, 237. 18:4ff 832. A deviation from Paschen's law in mercury vaponr. (Great
Britain) While investigating the electrical properties of mercury at low pressures, a linear relationship was found between the minimum breakdown potential and the electrode separation. G D N Overton, et al, Brit J Appl Phys, 16 (5), May 1965, 731-732. 18:40' 833. Primary ionization coefficients in mercury vapour at low pressures using a pool cathode. (Great Britain) The Townsend ionization coefficients in mercury vapour, using a mercury pool cathode under uniform field conditions, are presented and compared with previously obtained values. D E Davies and D Smith, Brit J Appl Phys, 16 (5), May 1965,
697-701. 19. Radiation
18. Gaseous electronics 18 : 33 829. Ion distribution in the drift region of tubular electron beams.
(Great Britain) In the drift region of a tubular electron beam, ions are focussed on the centre of the beam by the space charge force of the beam electrons, the ions being formed by electron-molecule collisions in
19 : 51 834. Test of the constancy of the velocity of electromagnetic radiation in high vacuum. (USA) An experiment with coherent light reflected from a moving mirror was performed at a pressure less than 10 -e torr, the result being consistent with the constant velocity of light. P Beckmann and P Mandics, J Res Nat Bur Stand, 69D (4), April
1965, 623-628. 521