Inreased Power Concentration and its Effect on the Discharge Parameters on the Low Pressure Hg‐Rare Gas Positive Column III. Effects of an Axial Rod

Abstract

After the investigation of the influence of current and tube radius on the power concentration of the Hg-rare gas discharge in the two previous parts, part I11 deals with the corresponding effects of additional recombination surfaces. The plasma parameters (radiant flux of the resonance lines, field strength, electron density, electron energy distribution function) are measured in a discharge tube with an axial glass rod. With increasing rod diameter and increasing distance from the tube axis radial radiation intensity distribution becomes asymmetric. The field strength increases with the radius of the rod. The dependence of the field strength and that of the radiant flux on the parameters of the discharge do not basically change. The measured UV-radiation efficiency of the positive column is higher than that of discharges without axial rod for equal tube radius. This is attributed primarily to the changed radial electron density distribution and its effect on the collision processes.

Spectral radiance of strong lines in positive column mercury discharges with argon carrier gas

“…The form of the dependence of electric field on discharge current (figure 17) is similar to that found in a 38 mm diameter lamp by Kreher and Stern [9], but our field strengths are somewhat higher. This is qualitatively consistent with the finding of Kreher and Stern in a second paper [10] that field strength increases significantly when the lamp diameter is reduced from 38 to 22 mm.…”

A study of radial cataphoresis and ion densities in high power density Hg–Ar discharges

“…Numerical models are playing an increasingly important role in the further development of fluorescent lamp technology (e.g. Waymouth and Bitter (1956), Cayless (1963), Winkler et al (1983), Dakin (1986), Kreher and Stern (1988), Kreher and Stern (1989), Maya and Lagushenko (1989), Lister and Coe (1993), Zissis et al (1992)). Plasma models, which have been optimized under standard fluorescent lamp conditions, have not yielded agreement with experiments for high power density Hg-Ar discharges (Curry et al 2002).…”

Experimental and numerical study of a low-pressure Hg Ar discharge at high current densities

“…The significance of high power loading has already been mentioned. In addition, the buffer gas pressure in the experimental cell is about an order of magnitude lower than the buffer gas pressure in the so-called 'standard' Hg-Ar discharge and is lower than the range studied in other work on highly-loaded Hg-Ar discharges [9,10]. The much larger radius sets it apart from work on compact fluorescent lamp discharges [15].…”

“…One of the first self-consistent numerical implementations of Schottky's positive column model [1] was developed by Waymouth and Bitter [2] to describe a Hg fluorescent lamp discharge. Increasing sophistication in the treatments of radial variations in the positive column, radiation transport, multi-step excitation and ionization, and non-Maxwellian electron energy distributions have been achieved in subsequent models [3][4][5][6][7][8][9][10].…”

“…Standard positive column models (see section 4) have been less successful in reproducing experimental measurements for highly loaded lamps [15,16]. However, more complex kinetic models have reproduced many of the experimentally measured parameters such as electric field and radiative output for a wide range of power loading in discharges with buffer gas pressures of 1 Torr and greater [9,10]. Electrodeless lamps operate at pressures well below 1 Torr, for which there have been a number of experimental measurements [17][18][19][20][21] but numerical models have to date been unable to describe these discharges adequately.…”