Modelling of high-frequency electrodeless lamps. Comparison to experimental data.
N. Denisova , G.Revalde, A. Skudra2
1 Institute of Theoretical and Applied Mechanics, Novosibirsk, Russia
2 Institute of Atomic Physics and Spectroscopy, University of Latvia, Raina blvd. 19, Riga, Latvia
Abstract. Numerical and experimental investigations of high-frequency electrodeless lamps in argon, helium and argon- mercury mixtures are performed. The basic physical model and numerical codes of the high-frequency electrodeless discharge lamp (HFEDL) used for spectroscopic applications are developed. The model combines calculations of electromagnetic field profiles and plasma parameters including detailed kinetics of excited atomic states. A method of the self-consistent numerical solution for the plasma+HF field system is proposed. The method takes into account a temporal hierarchy of the kinetic processes in the discharge plasma. A stationary collision-radiative model is developed considering the following equations: (i) the transport equations for the electrons, (ii) the electron energy balance equation, (iii) the population rate equations for balance in the excited states and (iiii) the electromagnetic field equations. Based on the developed model, the radiation characteristics of the discharge plasma are calculated.
The intensities of the helium lines 587.6 nm and 728.1 nm are calculated, and are found to be in good agreement with the experimental data.
The relative intensities of the visible triplet of mercury lines of the wavelengths nm, nm, nm () and the resonance line nm () are calculated. Numerical simulation of the line intensities behavior in dependence on the mercury pressure, HF generator current and argon filling pressure is performed. The model results are in qualitative agreement with the experimental data.
Radial emission properties of high-frequency electrodeless discharge lamps in argon-mercury mixtures are investigated both, numerically and experimentally. The radial profiles of the intensities of the mercury triplet lines 404.7nm, 435.8nm and 546.1nm are measured for two different values of the high-frequency generator power. A model describing physical processes in a HFEDL, including the calculation of radial plasma parameters, is developed. Radial intensity dependences of the lines 404.7nm, 435.8nm and 546.1nm are calculated and are found to be in a good agreement with the experimental measurements. For all three visible triplet lines, we observed experimentally and numerically the decreased emission intensity from the axial part of the lamp at higher discharge powers.