Axial mercury segregation in direct current operated low-pressure argon–mercury gas discharge: Part II. Model

Due to cataphoresis, axial segregation of mercury will occur when the gas discharge of a fluorescent lamp is operated by means of a direct current. A consequence of this is a non-uniform axial luminance distribution along the lamp. To determine the degree of axial mercury segregation experimentally, axial luminance distributions have been measured which are converted into axial mercury vapour pressure distributions by an appropriate calibration method. The mercury segregation has been investigated for variations in lamp tube radius (3.6–4.8 mm), argon buffer gas pressure (200–600 Pa) and lamp current (100–250 mA) at mercury vapour pressures set at the anode in the range from 0.2 to 9.0 Pa. From the experiments it has been concluded that the mercury vapour pressure gradient at any axial position for a certain lamp tube diameter, argon pressure and lamp current depends on the local mercury vapour pressure. This observation is in contrast to assumptions made in earlier modelling publications in which one mercury vapour pressure gradient is used for all axial positions. By applying a full factorial design, an empirical relation of the mercury segregation is found for any set of parameters inside the investigated parameter ranges.

[1]  J. Mizeraczyk,et al.  Spectroscopic study of cataphoresis in He-Cd mixtures: Cd source-anode region , 1992 .

[2]  M. Druyvesteyn.  The electrophoresis in the positive column of a gas discharge , 1935 .

[3]  H. Morgenroth.  Über die Elektrophorese in Argon–Quecksilber‐Niederdruckentladungen , 1959 .

[4]  J. Gaur,et al.  Cataphoresis and Nitrogen‐Removal Processes for dc Discharges in He–N2 Mixtures , 1971 .

[5]  J. D. Ramshaw.  Hydrodynamic Theory of Multicomponent Diffusion and Thermal Diffusion in Multitemperature Gas Mixtures , 1993 .

[6]  A multi-domain boundary-relaxation technique for the calculation of the electromagnetic field in ferrite-core inductive plasmas , 2002 .

[7]  A. Hartgers,et al.  Modelling an Ar-Hg fluorescent lamp plasma using a 3 electron-temperature approximation , 2001 .

[8]  D. S. Remer,et al.  A Theoretical Model for Gas Separation in a Glow Discharge: Cataphoresis , 1968 .

[9]  van der Hwp Harm Heijden,et al.  A self-consistent LTE model of a microwave-driven, high-pressure sulfur lamp , 2002 .

[10]  R. Hackam.  Effects of steady‐state electrical discharge on the separation of gas constituents in helium‐argon mixture , 1973 .

[11]  E. F. Tubbs,et al.  Use of Cataphoresis to Determine Discharge Parameters , 1963 .

[12]  R. Hackam.  Study of cataphoresis in the positive column of an argon‐neon discharge , 1974 .

[13]  H.W.P. van der Heijden,et al.  Radiative transfer of a molecular S2 B-X spectrum using semiclassical and quantum-mechanical radiation coefficients , 2002 .

[14]  J. V. D. Mullen,et al.  Semiclassical and quantum-mechanical descriptions of S2 molecular radiation , 2001 .

[15]  J. Gaur,et al.  Ionic Analysis of Cataphoresis in He–Ne Mixtures , 1969 .

[16]  A. V. Phelps,et al.  MOMENTUM TRANSFER CROSS SECTIONS FOR SLOW ELECTRONS IN HE, AR, KR, AND XE FROM TRANSPORT COEFFICIENTS, , 1964 .

[17]  L. M. Chanin,et al.  Cataphoretic segregation effects in Ne–Hg and Ne–Xe–Hg mixtures , 1973 .

[18]  J. Maya,et al.  Progress In Low Pressure Mercury–Rare-Gas Discharge Research , 1989 .

[19]  J. Lawler,et al.  Experimental and numerical study of a low-pressure Hg–Ar discharge at high current densities , 2002 .

[20]  J. Gaur,et al.  Ion Sampling from the Positive Column of dc Discharges in He–Ar Mixtures , 1970 .

[21]  T. Sosnowski.  Cataphoresis in the Helium‐Cadmium Laser Discharge Tube , 1969 .

[22]  J. H. Ingold,et al.  Axial particle density gradient in direct‐current discharges , 1984 .

[23]  A. Hartgers,et al.  Implementation of a friction-based self-consistent multicomponent diffusion model in Plasimo , 2003 .

[24]  R. Crompton,et al.  The Momentum Transfer Cross Section for Electrons in Argon in the Energy Range 0–4 eV , 1977 .

[25]  M. A. Biondi,et al.  Mobilities of Mercury Ions in Helium, Neon, and Argon , 1957 .

[26]  C. C. Johnston,et al.  Operational trends in the temperature of a high-pressure microwave powered sulfur lamp , 2002 .

[27]  K. Krysmanski.  Gasentmischungsvorgänge in Gleichstromglimmentladungen , 1958 .

[28]  L. M. Chanin,et al.  Complex ion formation in Xe–Hg mixtures , 1972 .

[29]  A. Metze,et al.  Theoretical modeling of time‐dependent cataphoretic gas separation in direct‐current gas discharges when end volumes are present , 1980 .

[30]  Donald S. Cohen,et al.  Transient ordinary and forced diffusion in a tube connecting stirred-tank end bulbs of finite size , 1969 .

[31]  J. Freudenthal.  Axial gas transports in DC-discharges in mixtures of gases , 1967 .

[32]  D. Uhrlandt,et al.  Model of a He–Xe low-pressure dc positive column plasma , 2003 .

[33]  F. R. Kovar.  Mobility of Mercury Ions in Mercury Vapor , 1964 .

[34]  A. Schmeltekopf.  Cataphoresis in Helium‐Neon Mixtures , 1964 .

[35]  R. P. Riesz,et al.  THE ANALYSIS AND PURIFICATION OF RARE GASES BY MEANS OF ELECTRIC DISCHARGES , 1954 .

[36]  A. Metze,et al.  The use of spectroscopic measurements to evaluate cataphoretic segregation , 1979 .

[37]  E. Baly.  XXIV.Separation and striation of rarefied gases under the influence of the electric discharge , 1893 .

[38]  C. Sanctorum.  Cataphoresis in neon-argon mixtures , 1976 .

[39]  Bernat,et al.  Modeling the Hg-Ar low-pressure-discharge positive column: A comparative study. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[40]  H. C. Miller.  Cataphoretic Purification of Neon , 1964 .

[41]  J. V. D. Mullen,et al.  General treatment of the interplay between fluid and radiative transport phenomena in symmetric plasmas: the sulphur lamp as a case study , 2002 .

[42]  H. J. Oskam.  Remarks concerning the theory of the segregation of gases in direct current discharges due to ion flow , 1969 .

[43]  A. Robertson.  The momentum transfer cross section for low energy electrons in neon , 1972 .

[44]  J. Freudenthal.  Cataphoretic Purification of Gases , 1967 .

[45]  J. Waymouth.  Electric Discharge Lamps , 1971, Nature.

[46]  H. J. Oskam,et al.  Volume Forces in Plasmas , 1967 .

[47]  S. E. Coe,et al.  GLOMAC : a one dimensional numerical model for steady state low pressure mercury-noble gas discharges , 1993 .

[48]  van der Jjam Joost Mullen,et al.  Thomson scattering on a low-pressure, inductively-coupled gas discharge lamp , 2002 .

[49]  J. Freudenthal.  Cataphoresis and collision processes in low-pressure discharges , 1967 .

[50]  L. Loeb.  Mechanism of Cataphoretic Segregation in Inert Gas Glow Discharges , 1958 .