0000000000451601
AUTHOR
Natalia Denisova
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 investigatio…
A study of capillary discharge lamps in Ar–Hg and Xe–Hg mixtures
Low-pressure capillary discharge lamps in Ar–Hg and Xe–Hg mixtures are studied. The discharge size is 0.5 mm (500 µm) in radius. According to the literature, such types of plasma sources are classified as microplasmas. The studies include spectrally resolved optical measurements, tomographic reconstructions and numerical simulations using the collisional–radiative model for an Ar–Hg plasma. We discuss the problems of theoretical modelling and experimental diagnostics of microplasma sources. It is shown that the conventional collisional–radiative model, based on the assumption that transportation of atoms in the highly excited states can be neglected, has limitations in modelling a capillary…
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.
A study of physical processes in microplasma capillary discharges
We continue the research of low-pressure capillary discharge lamps of 500 μ m in radius in Ar/Hg, Kr/Hg and Xe/Hg mixtures. In the previous paper, an experimental approach which combines the optical emission spectroscopy (OES) and tomographic methods was developed to study the capillary discharge. The present work is focused on interpretation of the tomographic reconstruction results for understanding the physical processes occurring in a capillary plasma. Analyzing the results of reconstruction, it was concluded that the radial profiles of Ar, Kr and Xe emission coefficients are in a good agreement with the Schottky theory. According to the Schottky model, ionization processes in plasma a…
Spatial Diagnostics of Hg/Ar and Hg/Xe Discharge Lamps by Means of Tomography
In this work, the diagnostics using tomography in Hg/Xe and Hg/Ar capillary lamps is presented. First, the imaging of the lamps was performed using selected emission lines of mercury, argon and xenon in different operation conditions. Thus the tomographic reconstruction was made, to determine the spatial distribution of the emitting Hg and rare gas atoms. Significant differences of the distribution of the emitting atoms have been found in vertical and horizontal operation positions. The emitting mercury atoms in the state 73S1 were differently distributed within the lamp in the vertical and horizontal lamp positions. The radial profile has demonstrated a substantial depletion of the popula…
Diagnostics of capillary mercury–argon high-frequency electrodeless discharge using line shapes
Abstract The profiles of the 253.7 nm spectral line, emitted from the capillary argon–mercury isotope high-frequency electrodeless discharge, are measured by means of a pressure-scanned Fabry–Perot spectrometer. Spectral line profiles are collected from two lamps at the argon pressure of 2 and 10 Torr, in dependence on the discharge current and Hg vapor densities corresponding to the cold spot temperatures of 25–80 °C. By means of a multi-parameter non-linear line profile fitting procedure of multiple overlapping self-reversed Voigt profiles, the temperature of the radiating atoms and the optical density were estimated. The capillary and spherical discharge conditions were compared. The opt…