Acta Technica 68. (1970)

1-2. szám - Bitó, J. F.: Dependence of Cathode Properties on Neon Doping and Discharge Current

Acta Technica Academiae Scientiarum Hungaricae; Tomus 68 (12), pp. 29 — 49 (1970) DEPENDENCE OF CATHODE PROPERTIES ON NEON DOPING AND DISCHARGE CURRENT J. F. BITÓ CAND. OF TECHN. SC. RESEARCH INSTITUTE FOR ELECTRONICS, BUDAPEST I Manuscript received November 5, 1968] Up to the present time no experimental data have been published concerning the influence of neon-gas doping on the cathode properties of mercury vapour-argon discharges. In the course of our experiments it was possible to demonstrate the dependence of cathode fall, cathode spot temperature, length of cathode side spaces, the field strength of the positive column, the voltage drop and power consumption of the discharge tube on the partial pressure of neon. Furthermore the dependence of cathode properties on the discharge current has also been determined. The relationships obtained in the experiments have been interpreted in terms of the known plasmaphysical data. I. Introduction In the improvement of light utilisation (efficacy) of fluorescent lamps, and in increasing their specific power consumption (power on unit discharge path), neon is almost exclusively employed in addition to argon as a dope gas, in a suitable per cent to meet the particular requirements [1]. As has been demonstrated [1], neon has the capacity of increasing the share of positive column in the total power consumption of the discharge [1]. Among others this accounts for the fact that today neon is employed as a dope gas. However, the effects on the cathode side associated with its uses have as yet not been elucidated. The literature [1—3] contains only so much information that the life of the cathode coating and hence the life of the discharge tube as a whole, is reduced considerably with increasing amounts of neon doping added. Bernier and Gungle [4] also carried out probe measurements in the vicinity of the cathode providing some information on the influence of neon doping on cathode fall and on the ion current (under conditions not fully elucidated). They wished to establish from the investigations the influence of filament voltage on the cathode in an argon-neon gas atmosphere, by employing a special electrode structure. Their objective was to utilise the results of investigations in the design of a new cathode structure. Published in the same source [4], those authors tried to establish relationships between the arcover stresses in argon and in neon-argon discharges and the cathode fall. However, no author has so far published information, for instance, on the unequivocal influence on cathode fall — a point of great significance for the usefulness of neon gas. Aria Trchnica Academiae Scienliarum Hungaricae 68, 1970

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