Stark broadening of halogen atom lines from (1 D)n p levels

We report results of a study of the Stark broadening of halogen atom lines from (¹ D)n p levels. Wall stabilized arc is used as a plasma source. Electron densities 2.2–3.2×10²² m^?3 are determined from the width ofH _α line and electron temperature 9300–10000 K from plasma composition data. The agreement with the results of simple semiclassical calculations is within the limits of the estimated errors of both experiment and theory. An explanation for the large discrepancy between theory and experiment detected for three BrI lines is offered.     

Stark shift and broadening of FI and ClI lines

We report measured Stark shifts and widths of neutral flourine and chlorine lines. Wall stabilized arc is used as a plasma source. Electron densities 2–4×10²² m^?3 are determined from the width of theH _β line and electron temperatures 9500–10 000 K from plasma composition data. Experimental results for FI and ClI Stark widths and FI Stark shifts agree within 10% with semiclassical calculations. ClI Stark shifts are systematically smaller for about 20% than theoretical data with the only exception of the line from multiplet no. 15 where the discrepancy goes up to 49%. Results of investigation of similarities and regularities of Stark widths are in agreement with the study of Wiese and Konjevi?. Comparison of experimental Stark shifts shows certain types of regularities.     

A simple line shape technique for electron number density diagnostics of helium and helium-seeded plasmas

The results of an experimental study of the He I 447.1 nm line and its forbidden component at high electron number density are presented and compared with profiles calculated using computer simulation method. Michelson interferometer at 632.8 nm was used to measure plasma electron number density in the range (1–7) × 10²³ m^− 3 while electron temperatures for the same experimental conditions in the range of 25 000 K to 35 000 K were determined using several spectroscopic techniques. The agreement of experimental overall line shape with computer simulation results is within 10% of what is well within theoretical and experimental uncertainty. This favorable comparison enabled the development of a simple approximate formula for the evaluation of electron number density from the measurement of wavelength separation between peaks of allowed and forbidden lines. This technique of plasma diagnostics is not sensitive to the presence of self-absorption of strong He I allowed line. The derivation of approximate formula with estimated accuracy of 15% was followed by detailed comparison with other experimental and theoretical data.     

Excessive hydrogen and deuterium Balmer lines broadening in a hollow cathode glow discharges

Results of a Doppler spectroscopy study of hydrogen and deuterium Balmer lines in the stainless steel and copper hollow cathode glow discharge, operated in pure hydrogen, deuterium and mixtures of inert gases with hydrogen, are reported. For all gases and gas mixtures plasma observations perpendicular to electric field revealed the excessively large Doppler broadening. By changing mode of glow discharge operation, the Doppler broadened line profiles in helium-hydrogen mixture are recorded parallel to the discharge electric field as well. The excessively broadened part of the H line profile is shifted towards blue or red wavelength by changing the direction of electric field vector. The presence of large excessive Balmer lines broadening in pure hydrogen and in its gas mixture with neon as well as shifting of the excessively broadened part of line profile by means of electric field is in contradiction with the resonance transfer model proposed by Mills et al. in several publications, see e.g. [IEEE Trans. Plasma Sci. 31, 338 (2003)].     

On Modeling of the Spectral Line Shape of Heavy Neutral Nonhydrogen-Like Emitters

A method of simulating the contour of the asymmetric spectral lines of neutral nonhydrogen-like atoms in a plasma is suggested. The methods of nonlinear regression are used to approximate the experimental data by a model function. The method has been checked on the spectral lines emitted by the electric arc stabilized by the walls. The method makes it possible to evaluate the Stark parameters directly from the experimentally obtained shapes of isolated or overlapping spectral lines.     

Spectroscopic diagnostics of laser-induced plasmas

An overview of spectroscopic diagnostics techniques for low temperature plasmas is presented with an emphasis to electron number density — N_e measurement. Stark broadening of non-hydrogenic atom and positive ion spectral lines is given. The attention is drawn to experimental techniques used for line intensity and line profile measurement. Self-absorption test, importance of Abel inversion, deconvolution of experimental line profiles and measurement of line asymmetry are treated in some detail in order to improve N_e measurements. Finally the sources of theoretical and experimental Stark broadening data are reviewed and some details discussed.     

Wavelength tuning of nitrogen pumped dye laser

In this paper a method is described for continuous wavelength tuning of nitrogen pumped dye laser by changing the concentration of an additional dye in the lasing solution.     

Electron density measurements during a current perturbation of a wall stabilized argon arc

The paper describes the application of a laser interferometric technique to the measurement of electron density changes which occur when a d.c. argon arc is subjected to a current step or a.c. modulation. The frequency of the latter was varied from 50 to 30,000 Hz. A first attempt is made to derive mobility measurements from the data.     

Determination of some transport properties of argon from transient arc behaviour

A new method is described which enables the electrical conductivity and electron mobility to be derived from the measurement of either the decay, following interruption, or response of a wall stabilized arc to a step change in current. This has been achieved by using a laser interferometer to record the corresponding change in electron density. The method has been applied to arcs of different radii and the derived transport properties are given in the range 8,800–12,200 °K for argon at atmospheric pressure.     

CO2 Laser-induced plasma formation on a copper surface covered by dielectric particles

The results of an experimental study of TEA CO₂ laser plasma formation in front of a copper surface covered by crystallites of sodium chloride are reported. It is found that the threshold laser-beam intensities for plasma formation depend upon the mean surface concentration of sodium chloride. The results obtained are explained within the frame of a thermal model of surface-plasma formation.