A collisional radiative model for mercury in high-current discharges

Abstract

A collisional radiative model is presented for mercury discharges with electron temperatures between 0.75-2 eV and electron densities between 1018-1020 m-3. Such plasma parameters are encountered in a number of modern light sources, such as mercury-operated induction lamps and the compact fluorescent lamp. The analytical top model has been used, which allows the majority of the non-equilibrium levels to be taken into account implicitly. As a result, indirect ionization processes involving highly excited atomic mercury states are taken into account in spite of the relatively low number of levels (19) which has been considered. The influence of higher atomic mercury levels on the ionization rate coefficient has been carefully analysed, and has been found to contribute significantly. Furthermore, a consistent means of quantifying the production of radiation by the plasma will be presented by introducing the specific effective emissivities. These enable one to express the total radiated power in terms of the densities of the transport-dominated states and the electron density and temperature. These coefficients, as well as the net coefficients of ionization and recombination, will be presented and discussed, enabling their usage in plasma transport models.

Absorption measurements on a low-pressure inductively coupled argon/mercury discharge for lighting purposes: 2. Electron density and temperature

“…These deviations decrease for higher electron densities [12,13], since the progressively increasing influence of the electron-electron Coulomb collisions will impose a Maxwellian EEDF. In forthcoming work [15] it will be shown that for electron densities above 10 19 m −3 the deviations from Maxwell are negligible.…”

“…The ionization coefficient of mercury for a Maxwellian EEDF has been calculated by Van Dijk et al [15] (…”

“…The data points and the fit are given in figure 5. The assumption of the Maxwellian EEDF will be discussed more extensively in [15]. The mercury density is determined by the mercury vapour pressure p Hg of the amalgam which is situated at the bottom of the lamp.…”

The plasma modelling toolkit Plasimo

“…For more details about the theory that underlies this technique and the calculation of the radiative and energy loss terms, we refer to [85]. References [85,87] demonstrate an application of this technique to mercury plasma with high degrees of ionization.…”

Analysis of Discharge Characteristics of Flat Fluorescent Lamps for a Large Area Backlight Unit using a Two-Dimensional Fluid Simulation

“…The fluid model consists of a set of fluid equations for electrons, ions (Hg þ , Ar þ , and Ne þ ), and excited state neutrals such as Hg à ( 3 P 1 ), Hg à ( 1 P 1 ), Hg à ( 3 P 0 ), Hg à ( 3 P 2 ), Hg Ãà , Ar à , and Ne à . 16,18,21) The densities of charged particles are coupled self-consistently with Poisson's equation. The Hg, Ar, and Ne gas densities are assumed to be uniformly distributed according to a specified neutral pressure in the FFL.…”