Positive column of Na-Ne-Ar ac discharges

Abstract

The positive column of 50-Hz ac discharges in a mixture of sodium vapor and noble gas (99 vol% Ne–1 vol% Ar) has been investigated experimentally. The experimental conditions were as follows: discharge tube radius 10 mm, noble-gas pressure 5.5 Torr at 20°C, and sodium density (2.4–5.7) × 1019 m−3 which corresponds to a tube wall temperature of 519–538 K. The rms values of the current ranged from 0.25 to 1.5 A. The discharge properties, measured with the aid of electrostatic probes, show hysteresis effects especially for high rms current values. This behavior can be explained from the combined effects of depletion of sodium atoms and diffusion. It is found that the experimental data on the time-resolved electron temperature agree with calculated values. Qualitative agreement is obtained between the measured and calculated data on the electron density, electric field strength, and radiated power.

Low-pressure sodium discharge lamps

“…34 Measured V/l curve for sodium/rare-gas discharge showing its multivalued character [50] -t(ms) Fig. 35 Measured electric field E, electron temperature T e and axial electron density N e in sodium-neon discharge [53] 900 mA, 50 Hz, tube diameter 19 mm, neon pressure 730 Pa, tube-wall temperature 530 K and electron density have also been carried out on a discharge operating on a 50Hz supply [52,53]. Fig.…”

“…It can be seen that there is a substantial amount of asymmetry in the data. This is due to the fact that the radial ambipolar and neutral atom diffusion time constants, which determine the depletion phenomena, are comparable with the half-cycle time of the mains of 10ms [52,54].…”

Studies concerned with improvement of the low pressure sodium discharge lamp

“…The local sodium vapour density can also be determined using other techniques each method having its specific advantages and disadvantages. 3 Lamp voltage control during life With the low pressure sodium discharge lamp one problem which tended to arise was an increase in the lamp voltage during the life of the lamp. If, using the diagnostic techniques in Section 2.…”