Atis Skudra

High-frequency electrodeless lamps in argon-mercury mixtures

In this paper, numerical and experimental investigations of high-frequency (HF) electrodeless lamps in argon–mercury mixtures are performed. The intensities of the mercury spectral lines having wavelengths λ = 404.66, 435.83, 546.07 nm (7 3S1–6 3P0,1,2) and the resonance line λ = 253.7 nm (6 3 P1–6 1S0) are measured at a wide range of mercury pressures, varying the HF generator current and argon filling pressure. A stationary self-consistent model of HF electrodeless discharge lamp is developed including kinetics of the excited mercury and argon atomic states. Based on the developed model, the radiation characteristics of the discharge plasma are calculated. Numerical simulation of the line intensities behaviour 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. The calculations of the relative intensities of the visible triplet lines 7 3S1–6 3P0,1,2 are presented for the first time in this paper.

MATHEMATICAL MODELLING OF THE SPECTRAL LINE PROFILES IN THE HIGH-FREQUENCY DISCHARGE

Abstract The paper is devoted to an estimation of the true profiles of spectral lines and equipment influence based on complex experimental line shape profiles in high-frequency discharge by means of a non-linear multiparameter chi-square fit. The self-absorption and energy transfer effects are taken into consideration. A good agreement with interferometric data from Hg and Hg–Cd high-frequency electrodeless lamps of both natural and isotopic abundance are achieved. The temperature of radiating atoms and the optical density for several lines are obtained as a function of the high-frequency oscillator working regime. The confidence regions, standard deviations and correlations of parameters are obtained using statistical modelling.

Optimization of mercury vapour pressure for high-frequency electrodeless light sources

Radiation qualities of mercury high-frequency electrodeless light sources (HFELSs) of natural and 202 isotope abundance of 99.8% have been studied in order to optimize filling and operation of the source. The optimal mercury vapour pressure in a high-frequency electrodeless inductive coupled discharge is estimated. A qualitative explanation of the excitation and ionization processes is given. An application of nonlinear multiparameter chi-square line shape fitting in order to find the true profile of spectral lines and equipment influence is presented. We demonstrate that, by appropriate selection of both the HF-oscillator working mode and Hg vapour pressure, it is possible to change the intensity and profile of the spectral lines quickly, making the use of the mercury HFELSs in various applications possible.

Tomographic diagnostics of high-frequency electrodeless lamps in argon-mercury mixtures

Tomographic reconstruction of spatial profiles of the mercury atom density in the excited state 7 3S1 in high-frequency electrodeless lamps (HFELs) has been performed. The measurements of the Hg 546.1 nm line emission intensity have been made for the HFELs in argon–mercury mixture depending on the operation regime with different cold spot temperatures in the range 31–98 °C. The maximum entropy-based algorithm was applied for the reconstruction of local emission coefficients from the integrated intensities. The emission coefficients are directly related to the local values of the mercury atom density in the excited state 7 3S1, the upper state of the 546.1 nm transition. Such an investigation has been performed first for the HFEL. We have found that the emitting mercury atoms in the state 7 3S1 are concentrated in a thin layer located close to the lamp wall. The radial profiles have demonstrated a strong depletion of the population density in the state 7 3S1 from the lamp centre at high generator currents and low mercury vapour density. The obtained results are analysed theoretically in the context of the radial cataphoresis phenomenon. We found a qualitative agreement between the reconstructed density profiles and theoretical model predictions.

Plasma Temperature Determination of Hydrogen Containing High-Frequency Electrodeless Lamps by Intensity Distribution Measurements of Hydrogen Molecular Band

The goal of the present work was the investigation of the possibility to use intensity distribution of the Q-branch lines of the hydrogen Fulcher- diagonal band ( electronic transition; Q-branch with ) to determine the temperature of hydrogen containing high-frequency electrodeless lamps (HFEDLs). The values of the rotational temperatures have been obtained from the relative intensity distributions for hydrogen-helium and hydrogen-argon HFEDLs depending on the applied current. The results have been compared with the method of temperature derivation from Doppler profiles of He 667.8 nm and Ar 772.4 nm lines. The results of both methods are in good agreement, showing that the method of gas temperature determination from the intensity distribution in the hydrogen Fulcher- (2-2)Q band can be used for the hydrogen containing HFEDLs. It was observed that the admixture of 10% hydrogen in the argon HFEDLs significantly reduces the gas temperature.

Study of the dependence of the radiative properties of high-frequency electrodeless lamps in an Hg-Ar mixture on the pressure of mercury vapor

The radiative characteristics of high-frequency electrodeless lamps in a mixture of mercury and argon have been studied theoretically and experimentally as functions of the cold spot temperature (the pressure of mercury vapor). The intensity of the mercury lines at 404.7, 435.8, and 546.1 nm, corresponding to the triplet transition (73S1-63P0,1,2) in the visible spectral region, as well as the intensity of the UV resonance line (63P1-61S0) at 253.7 nm, has been measured. A model describing the physical processes in the discharge plasma and including the kinetics of excited states of mercury and argon atoms has been suggested. The parameters of the discharge plasma and the electromagnetic field have been calculated self-consistently through the numerical solution of the system of equations of electron density and energy balance and population balance of excited levels of argon and mercury atoms, as well as the Maxwell equations. The model developed has allowed us to calculate the intensities of the mercury emission lines at 253.7, 404.7, 435.8, and 546.1 nm and to compare the results with experimental data. The relative intensities of the mercury spectral lines corresponding to the triplet transition 73S1-63P0,1,2 have been calculated for the first time on the basis of a self-consistent model of the discharge.

Radial properties of high-frequency electrodeless lamps in argon–mercury mixtures

Radial emission properties of high-frequency electrodeless discharge lamps (HFEDLs) in argon–mercury mixtures are investigated both numerically and experimentally. The radial profile of the intensities of the mercury triplet lines 404.7, 435.8 and 546.1 nm are measured for two different values of the high frequency generator power. A model describing physical processes in an HFEDL, including the calculation of radial plasma parameters, is developed. Radial intensity dependences of the lines 404.7, 435.8 and 546.1 nm are calculated and are found to be in good agreement with the experimental measurements.

Radial characteristics of radiation of high-frequency electrodeless lamps

The radial dependences of the radiative characteristics of high-frequency electrodeless lamps (HFELs) using as a working medium either a mixture of mercury and argon or helium have been investigated in experiments and numerical simulations. The intensities of the mercury line at a wavelength of 546.1 nm and the helium line at 587.6 nm have been measured. The measurements were conducted at different points lying on the central chord of the circular end of a cylindrical lamp. As the power of the pumping generator increases, a decrease in the radiation intensity near the axis of the discharge in a mercury vapor HFEL is observed, while, in the helium lamp, on the contrary, the intensity increases. On the basis of models of HFELs developed earlier, we have calculated the radial dependences of the radiation intensity of the mercury line at 546.1 nm and the helium line at 587.6 nm. A satisfactory agreement with the data of experimental measurements has been attained. A comparative analysis has been carried out, and an explanation has been proposed for the difference in the observed radial intensity profiles of these two lines.

Imaging of Emitting Mercury Atom Spatial Distributions in a Capillary Discharge Lamp by Using Tomography Approach

A tomographic reconstruction of emitting mercury atom spatial profiles in a capillary lamp with an inner diameter of 1 mm has been made for the first time in this work. Measurements of emission intensity have been performed for the capillary lamp in a xenon-mercury mixture in dependence on the operation position. Intensities were measured for the 546.1-nm Hg line for vertically and horizontally operated lamps. We have found that the emitting mercury atoms in the state 73S1 (the upper state of the 546.1-nm transition) are differently distributed within the lamp in the vertical and horizontal lamp positions.

High-frequency electrodeless light sources for application

The high-frequency electrodes light sources (HFELS) are widely used as bright radiators of narrow and intensive spectral lines covering spectral region from VUV to IR. In this work we shall give a short overview of our experience in preparation of HFELS, containing He, H, Rb, Hg, Zn, Pb, As, Sb, Bi, Tl, Hg-Cd, Hg-Zn, Hg-Cd-Zn, Se-Te for different applications. Special attention would be paid for HFELS use in Zeeman mercury analyzer, in Atomic absorption analyzer and Angle and glass refractive index measurement system.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.