Some investigations of gas discharges by means of an exploring electrode

1927 ◽  
Vol 23 (5) ◽  
pp. 531-541 ◽  
Author(s):  
K. G. Emeléus
Keyword(s):  
Glow Discharge ◽  
Electric Field ◽  
Electron Current ◽  
Negative Glow ◽  
Gas Discharges ◽  
Slow Group ◽  
Dark Space ◽  
Current Densities ◽  
Fast Group

The glow discharge between cold aluminium electrodes in air, oxygen, nitrogen and hydrogen has been analyzed by Langmuir's method, for pressures between 0·1 and 0·4 mm. Hg, current densities of from 0·02 to 0·2 mA./sq.cm., and applied potentials between 300 and 700 volts. An annular exploring electrode has been used. It has been found that whilst practically the whole fall of potential is localized across the cathode dark space at the lower pressures, a fall of as much as 40 volts can exist across the remainder of the discharge at the higher pressures. Reversal of the electric field has been found in the negative glow, and in certain cases in the Faraday dark space, when conditions are favourable for passage of an electron current by diffusion against the field. In several instances the negative glow was at a higher potential than the anode. Two groups of electrons occur in the negative glow, together with a single fast group at the anode boundary of the cathode dark space, and a single slow group in the Faraday dark space.

scholarly journals Experiments on the length of the cathode dark space with varying current densities and pressures in different gases

1907 ◽  
Vol 79 (528) ◽  
pp. 80-95 ◽  
Keyword(s):  
Measurable Quantity ◽  
Negative Glow ◽  
Plane Parallel ◽  
Irregular Form ◽  
Dark Space ◽  
Current Densities ◽  
The Right ◽  
Different Gases ◽  
Aluminium Disc ◽  
A Current

During some experiments with various types of vacuum tubes the author was led by the behaviour of one in particular to believe that conditions were possible under which the length of the cathode dark space might be an accurately measurable quantity. This tube is shown in fig. 1. The aluminium disc cathode K is movable and exactly fits the tube containing the anode A. If it is placed to the right in the bulb and a current from a coil passed, tire dark space assumes a highly indefinite and irregular form, such as is indicated. If, however, K is slid to the left, right into the tube containing A, the boundary of the negative glow becomes a very definite plane parallel to the cathode, its distance from the cathode being the same for all positions of the latter so long as it is inside the tube and the current from the coil kept constant.

Optogalvanic Measurement of the Electric Field inside the Cathode Fall Region of Neon Hollow Cathode Discharge

1989 ◽  
Vol 43 (2) ◽  
pp. 245-248 ◽  
Author(s):  
Norihiro Ami ◽  
Akihide Wada ◽  
Yukio Adachi ◽  
Chiaki Hirose
Keyword(s):  
Glow Discharge ◽  
Electric Field ◽  
Hollow Cathode ◽  
Stark Effect ◽  
Cathode Surface ◽  
Hollow Cathode Discharge ◽  
Cathode Fall ◽  
Negative Glow ◽  
Optogalvanic Spectroscopy ◽  
The Difference

Radial distribution of the electric field in the cathode fall region of neon hollow cathode discharge has been derived through the observation of the linear Stark effect of the nd′ ( n = 10–12)-3 p′[½]1 transitions by two-step optogalvanic spectroscopy. The field strength was found to decrease monotonically from the cathode to the negative glow. The depth of the cathode fall region was 0.80 ± 0.05 mm, and the electric field at the cathode surface was 5.2 ± 0.2 kV/cm*—values which compare with the reported values of around 3–4 mm and 3–4 kV/cm in the cathode fall region of Ne glow discharge. The difference and similarity in the values of derived parameters are discussed.

The hollow-cathode effect and the theory of glow discharges

1954 ◽  
Vol 224 (1157) ◽  
pp. 209-227 ◽  
Keyword(s):  
Glow Discharge ◽  
Electric Field ◽  
Current Density ◽  
Hollow Cathode ◽  
Elementary Theory ◽  
Secondary Electron Emission ◽  
Space Charge Density ◽  
Cathode Fall ◽  
Space Length ◽  
Dark Space

The nature of the processes in the cathode dark space and the negative glow of a glow discharge is not well understood. Moreover, the existing theory leading to relations between the cathode fall in potential, the current density, the width of the dark space and the electric field distribution in it is based on dubious assumptions and does not indicate the important physical processes in operation. Thus further experimental evidence would be valuable in developing the theory. By exploring the electric field between two plane-parallel cathodes with an electron beam, and observing simultaneously the other discharge parameters, new information was obtained. A double (hollow) cathode was used because in a conventional glow discharge the dark space, cathode fall and current density are interdependent; here the cathode separation controls the width of the dark space. When the separation is sufficiently reduced the two negative glows coalesce and the light emitted as well as the cathode current density rise greatly. This is the hollow-cathode effect. Results show that the field in the two dark spaces of a hollow cathode falls linearly with the distance from the cathode, and thus the net space-charge density is constant, as it is known to be in the conventional discharge. From the same observations the dark-space length is found. The conclusions drawn from these results lead to an elementary theory which covers both the hollow and the conventional glow discharge in various gases as indeed it should, since with increasing cathode separation the first goes over into the second type. The main feature is the contribution of the ultra-violet quanta from the glow to the photo-electric emission from the cathodes which is regarded as the essential factor in secondary electron emission. Another result comes from a reconsideration of the motion of positive ions in the dark space based on atomic beam studies and the modem theory of elastic collisions between ions and atoms. The discrepancy between earlier experiments showing that ions of energy of the order of the cathode fall in potential arrive at the cathode and classical calculations leading to low ion energies is resolved by allowing for small-angle scattering and charge transfer.

scholarly journals Electric field distribution in the cathode sheath of an electron beam glow discharge

1987 ◽  
Vol 51 (6) ◽  
pp. 409-411 ◽  
Author(s):  
S. A. Lee ◽  
L.‐U. A. Andersen ◽  
J. J. Rocca ◽  
M. Marconi ◽  
N. D. Reesor
Keyword(s):  
Electron Beam ◽  
Glow Discharge ◽  
Electric Field ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Cathode Sheath

scholarly journals Statistical analysis of the dependence of large-scale Birkeland currents on solar wind parameters

2010 ◽  
Vol 28 (2) ◽  
pp. 515-530 ◽  
Author(s):  
H. Korth ◽  
B. J. Anderson ◽  
C. L. Waters
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Mach Number ◽  
Electric Field ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Dominant Factor ◽  
Total Current ◽  
Current Densities ◽  
Birkeland Currents

Abstract. The spatial distributions of large-scale field-aligned Birkeland currents have been derived using magnetic field data obtained from the Iridium constellation of satellites from February 1999 to December 2007. From this database, we selected intervals that had at least 45% overlap in the large-scale currents between successive hours. The consistency in the current distributions is taken to indicate stability of the large-scale magnetosphere–ionosphere system to within the spatial and temporal resolution of the Iridium observations. The resulting data set of about 1500 two-hour intervals (4% of the data) was sorted first by the interplanetary magnetic field (IMF) GSM clock angle (arctan(By/Bz)) since this governs the spatial morphology of the currents. The Birkeland current densities were then corrected for variations in EUV-produced ionospheric conductance by normalizing the current densities to those occurring for 0° dipole tilt. To determine the dependence of the currents on other solar wind variables for a given IMF clock angle, the data were then sorted sequentially by the following parameters: the solar wind electric field in the plane normal to the Earth–Sun line, Eyz; the solar wind ram pressure; and the solar wind Alfvén Mach number. The solar wind electric field is the dominant factor determining the Birkeland current intensities. The currents shift toward noon and expand equatorward with increasing solar wind electric field. The total current increases by 0.8 MA per mV m−1 increase in Eyz for southward IMF, while for northward IMF it is nearly independent of the electric field, increasing by only 0.1 MA per mV m−1 increase in Eyz. The dependence on solar wind pressure is comparatively modest. After correcting for the solar dynamo dependencies in intensity and distribution, the total current intensity increases with solar wind dynamic pressure by 0.4 MA/nPa for southward IMF. Normalizing the Birkeland current densities to both the median solar wind electric field and dynamic pressure effects, we find no significant dependence of the Birkeland currents on solar wind Alfvén Mach number.

scholarly journals Luminous vapour from the mercury arc and the progressive changes in its spectrum

1925 ◽  
Vol 108 (746) ◽  
pp. 262-279 ◽  
Keyword(s):  
Glow Discharge ◽  
Electric Field ◽  
Arc Discharge ◽  
The Other ◽  
Line Spectrum ◽  
Mercury Vapour ◽  
Band Spectrum ◽  
Other Hand ◽  
Continuous Band

It was observed originally by Stark that a stream of mercury vapour allowed to distil away from the arc or glow discharge in vacuo remains luminous. It may be said to carry the luminosity away with it, and in the case of the arc discharge there is no difficulty in detecting the luminosity for 50 cm. or so from the source. Stark found that when a glow discharge was used, which developed the continuous band spectrum, this spectrum could be detected in the distilled vapour, along with the line spectrum. When the glow was passed through an electric field, the line spectrum was found to be quenched, leaving the band spectrum unaffected. The arc discharge, on the other hand, gave only the line spectrum in his experiments.

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