Electrode fall and electric field measurements in high-pressure sodium discharges

Abstract

Measurements of the electric field and of the voltages of very short arc high-pressure sodium discharges (arc tube internal diameter 7.4 mm) have been used to estimate the electrode fall in high-pressure sodium lamps. These data are needed for the design of new ratings of high-pressure sodium lamp. Two methods have been used to avoid the systematic errors in field which result from depletion of the amalgam of sodium at high liquid amalgam temperatures. The electrode voltage fall is approximately independent of electrode construction for emitter coated electrodes at 4 ± 1 V. For pure tungsten electrodes it is 8 ± 1 V. The electrode fall is independent of discharge currents within the range 1-4.45 A.

On the plasma constriction close to the electrodes of high-pressure mercury and sodium lamps

“…To describe the energy transport to the cathode the knowledge of the temperature and density distribution of the plasma close to the electrode is necessary. Although such lamps are working well in several variations for decades and several studies have been published [1][2][3][4][5][6][7][8] concerning to the energy balance, the radiation output and the electrical behaviour, open questions concerning the transition zone between the plasma and the electrodes are still remaining. One of the main parameters that need to be determined is the temperature distribution and the spatial extension of the arc constriction.…”

Tin Sodium Halide Lamps in Ceramic Envelopes

“…In fact it is considerably higher than the values reported for the Sn-C1-I-Hg-A system. 17 We have also obtained energy balances for the same arc tube at powers between 50 W and 165 W. Of interest is the variation of arc radiation efficiency with input power (Fig. 13).…”

Energy balance of high-pressure sodium discharges under controlled vapour conditions

“…The balance between fractions of the input power dissipated by the arc by various processes (the 'energy balance') is shown in figures 5 , 6 and 7. The electrode loss is 4 times the lamp current, since the measured electrode voltage drop is 4 V (Denbigh and Wharmby 1976). The part labelled 'thermal conduction' is taken to be the difference between input power and the radiation and electrode loss, all radiated power having been measured.…”