Hydrogen Hα Line Research Articles

Laser-induced plasma analysis of ammonia-oxygen and ammonia-oxygen-enriched-air flames at elevated pressures

This study employed Laser-induced breakdown spectroscopy (LIBS) to measure the fuel-oxidizer ratio (FOR) of ammonia combustion with oxygen-enriched air and pure oxygen flames at elevated pressures (100 - 300 kPa). The correlations between the spectral line intensity ratios of nitrogen (N), hydrogen (H), oxygen (O), and equivalence ratio were used to quantify the FOR of flames at various pressures. The effect of pressure on the stability and precision of the calibration profiles for the elemental intensity ratios in flames was investigated. It was observed that the H/O correlation decreases with pressure increase for both ammonia flames. N/O correlations decrease with elevated pressure for the ammonia-oxygen flame. Furthermore, the nitrogen (NII) spectral emission lines at 568 nm and 595 nm were used to estimate the plasma temperature, while the hydrogen (Hα) line at 656 nm was used for electron number density measurements.

Transmission spectroscopy of WASP-7 b with UVES

Context. Transmission spectroscopy is a prime technique to study the chemical composition and structure of exoplanetary atmospheres. Strong excess absorption signals have been detected in the optical Na i D1, 2 Fraunhofer lines during transits of hot Jupiters, which are attributed to the planetary atmospheres and allow us to constrain their structure. Aims. We study the atmosphere of WASP-7 b by means of high-resolution transit spectroscopy in the sodium lines. Methods. We analyzed a spectral transit time series of 89 high-resolution spectra of the hot Jupiter WASP-7 b that was observed using the Ultraviolet and Visual Echelle Spectrograph (UVES). We used the telluric lines for an accurate alignment of the spectra and carried out a telluric correction with molecfit. Stellar magnetic activity was monitored by investigating chromospheric lines such as the Ca ii H and K, and hydrogen Hα lines. Finally, we obtained transmission spectra and light curves for various lines. Results. The star shows no identifiable flares and, if any, marginal changes in activity during our observing run. The sodium transmission spectra and corresponding light curves clearly show signs of the Rossiter-McLaughlin effect and the stellar center-to-limb variation that we modeled using synthetic spectra. A statistically significant, narrow absorption feature with a line contrast of 0.50 ± 0.06% (at ~8.3σ level) and a full width at half maximum of 0.13 ± 0.02 Å is detected at the location of the Na i D2 line. For the Na i D1 line signal, we derived a line contrast of 0.13 ± 0.04% (at ~3.2σ level), which we consider a tentative detection. In addition, we provide upper limits for absorption by the hydrogen Balmer lines (Hα, Hβ, and Hγ), K i λ7699 Å, Ca ii H and K, and infra-red triplet lines.

Prominence observations with ALMA

This review comes at the time when ALMA successfully obtained the first regular observations of both a prominence and a filament. These observations have a spatial resolution of 1-2 arcsec, far better than previous prominence observations in the mm/sub-mm radio domain. The achieved resolution is compatible with the cotemporal ground-based coronagraphic observations in the hydrogen Hαline that accompany the ALMA Band 3 prominence observations. A core part of this review is the description and analysis of these pioneering ALMA observations of a quiescent prominence, focusing on various physical and geometrical properties of the observed prominence fine structures. We also summarize the basic physical processes behind the formation of mm/sub-mm continua under prominence conditions and describe the plasma diagnostics potential of ALMA solar observations. Finally, we discuss future prospects of ALMA prominence observations and the value of coordinated optical and UV spectra and images.

Plasma temperature determination based on the ratio of plasma electron densities obtained from hydrogen Hα and Hβ spectral lines

Method for plasma electron temperature determination based on the ratio of electron densities obtained from hydrogen Hα and Hβ spectral lines based on electron densities ratio obtained from hydrogen Hα and Hβ spectral lines is considered. In order to verify its validity, the method was applied to wall stabilized DC and pulsed arc plasmas together with three other methods. Temperature range was 9600–13,600 K. The values obtained by applying the method presented in this paper differ from the average values obtained from all methods for <6%. Results are also in good agreement with the newer theories of Stark broadening of hydrogen spectral lines.

Laser induced breakdown spectroscopy for hydrogen detection in molybdenum at atmospheric pressure mixtures of argon and nitrogen

Present study investigated the effect of argon and nitrogen mixtures at atmospheric pressure on the hydrogen Hα line emission intensity during the Laser Induced Breakdown Spectroscopy (LIBS) measurements. LIBS is foreseen for the assessment of the fuel retention in ITER plasma facing components during the maintenance breaks when the reactor is filled with near atmospheric pressure nitrogen or dry air. The use of argon flow during LIBS measurements has shown to increase the LIBS signal at atmospheric conditions which aids the distinguishing of hydrogen isotopes. LIBS was used to ablate a small amount of molybdenum (Mo) target and the development of formed plasma plume was investigated by time-resolved emission spectra and photographs. Spectral measurements showed that the Hα line intensity and electron density decreased faster with the increased fraction of nitrogen in the background atmosphere. The electron temperature of created plasma was also lower in the nitrogen atmosphere. The spatial development of plasma plume was comparable in both argon and nitrogen atmospheres. According to these results, the reduction of Hα line intensity in the presence of nitrogen can be explained by higher fraction of energy consumption in dissociation and excitation processes of molecular gas and increased quenching of excited H states. Furthermore, the results demonstrate that a small amount of N2 impurities in Ar atmosphere does not have detrimental effect on LIBS measurements of hydrogen isotopes. Most of the local thermodynamic equilibrium (LTE) conditions required for the applicability of CF-LIBS were fulfilled in the time-window between 1-5 µs for Ar and 1-3 µs for N2 gas. One notable exception was the time-stability criterion for hydrogen atoms. The effect of this deviation from LTE on the applicability of CF-LIBS requires further studies.

Spectropolarimetric observations of the solar atmosphere in the Hα 6563 Å line

We present novel spectropolarimetric observations of the hydrogen Hα line taken with the Zürich Imaging Polarimeter (ZIMPOL) at the Gregory Coudé Telescope of the Istituto Ricerche Solari Locarno (IRSOL). The linear polarization is clearly dominated by the scattering of anisotropic radiation and the Hanle effect, while the circular polarization is dominated by the Zeeman effect. The observed linear polarization signals show a rich spatial variability, the interpretation of which would open a new window for probing the solar chromosphere. We study their spatial variation within coronal holes, finding a different behaviour for the U/I signals near the north and south solar poles. We identify some spatial patterns, which may facilitate the interpretation of the observations. In close-to-the-limb regions with sizable circular polarization signals, we find similar asymmetric Q/I profiles. We also show examples of net circular polarization profiles (NCP), along with the corresponding linear polarization signals. The application of the weak field approximation to the observed circular polarization signals gives 10 G (40–60 G) close to the limb quiet (plage) regions for the average longitudinal field strength over the spatio-temporal resolution element.

Quiet-Sun hydrogen Lyman-α line profile derived from SOHO/SUMER solar-disk observations

Context. The solar radiation in the Lyman-α spectral line of hydrogen plays a significant role in the illumination of chromospheric and coronal structures, such as prominences, spicules, chromospheric fibrils, cores of coronal mass ejections, and solar wind. Moreover, it is important for the investigation of the heliosphere, Earth’s ionosphere, and the atmospheres of planets, moons, and comets. Aims. We derive a reference quiet-Sun Lyman-α spectral profile that is representative of the Lyman-α radiation from the solar disk during a minimum of solar activity. This profile can serve as an incident radiation boundary condition for the radiative transfer modelling of chromospheric and coronal structures. Because the solar radiation in the Lyman lines is not constant over time but varies significantly with the solar cycle, we provide a method for the adaptation of the incident radiation Lyman line profiles (Lyman-α and higher lines) to a specific date. Moreover, we analyse how the change in the incident radiation influences the synthetic spectra produced by the radiative transfer modelling. Methods. We used SOHO/SUMER Lyman-α raster scans obtained without the use of the attenuator in various quiet-Sun regions on the solar disk. The observations were performed on three consecutive days (June 24, 25, and 26, 2008) during a period of minimum solar activity. The reference Lyman-α profile was obtained as a spatial average over eight available raster scans. To take into account the Lyman-α variation with the solar cycle, we used the LISIRD composite Lyman-α index. To estimate the influence of the change in the incident radiation in the Lyman lines on the results of radiative transfer models, we used a 2D prominence fine structure model. Results. We present the reference quiet-Sun Lyman-α profile and a table of coefficients describing the variation of the Lyman lines with the solar cycle throughout the lifetime of SOHO. The analysis of the influence of the change in the incident radiation shows that the synthetic spectra are strongly affected by the modification of the incident radiation boundary condition. The most pronounced impact is on the central and integrated intensities of the Lyman lines. There, the change in the synthetic spectra can often have the same amplitude as the change in the incident radiation itself. The impact on the specific intensities in the peaks of reversed Lyman-line profiles is smaller but still significant. The hydrogen Hα line can also be considerably affected, despite the fact that the Hα radiation from the solar disk does not vary with the solar cycle.

Sunquake with a second bounce, other sunquakes, and emission associated with the X9.3 flare of 6 September 2017

Aims.The 6 September 2017 X9.3 solar flare produced very unique observations of magnetic field transients and a few seismic responses, or sunquakes, detected by the Helioseismic and Magnetic Imager (HMI) instrument aboard Solar Dynamic Observatory (SDO) spacecraft, including the strongest sunquake ever reported. This flare was one of a few flares occurring within a few days or hours in the same active region. Despite numerous reports of the fast variations of magnetic field, and seismic and white light emission, no attempts were made to interpret the flare features using multi-wavelength observations. In this study, we attempt to produce the summary of available observations of the most powerful flare of the 6 September 2017 obtained using instruments with different spatial resolutions (this paper) and to provide possible interpretation of the flaring events, which occurred in the locations of some seismic sources (a companion Paper II).Methods.We employed non-linear force-free field extrapolations followed by magnetohydrodynamic simulations in order to identify the presence of several magnetic flux ropes prior to the initiation of this X9.3 flare. Sunquakes were observed using the directional holography and time–distance diagram detection techniques. The high-resolution method to detect the Hαline kernels in the CRISP instrument at the diffraction level limit was also applied.Results.We explore the availableγ-ray (GR), hard X-ray (HXR), Lyman-α, and extreme ultra-violet (EUV) emission for this flare comprising two flaring events observed by space- and ground-based instruments with different spatial resolutions. For each flaring event we detect a few seismic sources, or sunquakes, using Dopplergrams from the HMI/SDO instrument coinciding with the kernels of Hαline emission with strong redshifts and white light sources. The properties of sunquakes were explored simultaneously with the observations of HXR (with KONUS/WIND and the Reuven Ramaty High Energy Solar Spectroscopic Imager payload), EUV (with the Atmospheric Imaging Assembly (AIA/SDO and the EUV Imaging Spectrometer aboard Hinode payload), Hαline emission (with the CRisp Imaging Spectro-Polarimeter (CRISP) in the Swedish Solar Telescope), and white light emission (with HMI/SDO). The locations of sunquake and Hαkernels are associated with the footpoints of magnetic flux ropes formed immediately before the X9.3 flare onset.Conclusions.For the first time we present the detection of the largest sunquake ever recorded with the first and second bounces of acoustic waves generated in the solar interior, the ripples of which appear at a short distance of 5–8 Mm from the initial flare location. Four other sunquakes were also detected, one of which is likely to have occurred 10 min later in the same location as the largest sunquake. Possible parameters of flaring atmospheres in the locations with sunquakes are discussed using available temporal and spatial coverage of hard X-ray, GR, EUV, hydrogen Hα-line, and white light emission in preparation for their use in an interpretation to be given in Paper II.

Study of laser-induced-plasma parameters for molybdenum targets

Molybdenum targets were irradiated with 2-ns 300-mJ pulses from an Nd:YAG laser at its second harmonic wavelength of 532 nm at a repetition rate of 10 Hz in open air. The radiation emitted from laser-induced plasma from the Mo target in the Local Thermal Equilibrium (LTE) state was analyzed. The temperature of the plasma was calculated using a Boltzmann-plot method. The electron density was determined from the Stark broadening via the comparison of the electron densities of different neutral molybdenum lines (465.5, 498, 517 and 550 nm) with hydrogen Hα-line (656.3 nm). We studied the variation of electron density and electron temperature as a function of μs-delay times and laser fluencies at different distances from the target surface. It was found that the neutral molybdenum lines suffer from self-absorption. The self-absorption changes the values of the electron density and the electron temperature due to the decrease in the line intensity and the increase in the line width and hence leads to the distortion in the line shape. The Mo I lines were corrected against self-absorption and the corrected values of the temperature and the electron density were obtained.

Optical emission spectroscopy for studying the exploding copper wire plasma parameters in distilled water

This work aims to study the exploding copper wire plasma parameters by optical emission spectroscopy. The emission spectra of the copper plasma have been recorded and analyzed The plasma electron temperature (Te), was calculated by Boltzmann plot, and the electron density (ne) calculated by using Stark broadening method for different copper wire diameter (0.18, 0.24 and 0.3 mm) and currentof 75A in distilled water. The hydrogen (Hα line) 656.279 nm was used to calculate the electron density for different wire diameters by Stark broadening. It was found that the electron density ne decrease from 22.4×1016 cm-3 to 17×1016 cm-3 with increasing wire diameter from 0.18 mm to 0.3 mm while the electron temperatures increase from 0.741 to 0.897 eV for the same wire diameters. The optical emission spectrum (OES) emitted from the plasma have Hα line, small peak at 590 nm corresponding to sodium and others peaks belong to Cu I. The relationship between the plasma electron temperature, emission line intensity and number density with the formed copper nanoparticles size and concentration were studied. It was found that the nanoparticles concentration increase with emission line intensity while its size decrease. It can be conclude the existence of a controlled relationship between the plasma parameters and the formed nanoparticles concentration and size.

Optical emission spectroscopy investigation of the current sheet in a small-bore parallel-plate electromagnetic plasma accelerator

The optical emission spectrum of the propagating current sheet in a small-bore parallel-plate electromagnetic plasma accelerator has been studied. The accelerator is powered by a fourteen stage pulse forming network, which yields a damped oscillation square wave of current with a pulse width of 20.5 μs. The movement of the first current sheet and the second current sheet is identified using three single magnetic probes placed at various axial positions. Current sheet canting is measured by two double magnetic probes. The spectrum of the current sheet is measured using a spectroscopic system. The electron density of the current sheet plasma is determined via Stark broadening of the hydrogen Hα line. The current sheet is almost perpendicular to the electrode. The current sheet electron density increases as the current sheet propagates. The current sheet electron density is mainly determined by the prefill pressure rather than the discharge current. The impurity charged particles caused by ablation of the back wall insulator exists in the current sheet. Residual particles are generally left behind the first current sheet and are swept and ionized by the second current sheet. The estimated current sheet sweeping efficiency is greater than 80%. The parallel-plate electromagnetic plasma accelerator developed in this paper shows great potential in generating high electron density plasma jets.

Limit of detection and hardness evaluation of some steel alloys utilizing optical emission spectroscopic techniques

Steel alloys are of the most useful materials utilized in the manufacture of various industrial components. In this work, Laser-induced breakdown spectroscopy (LIBS) and spark-induced breakdown spectroscopy (SIBS) techniques have been used as diagnostic tools for the elemental composition of steel alloys and determination of the limit of detection (LOD). Also, the surface hardness of these alloys was measured using the ratio between the Calcium ionic and neutral lines (Ca II/Ca I) as well as the well-known method of mechanical Vickers one. The self-absorption of silicon, copper and calcium lines under investigation was corrected via comparison of the electron densities. The densities have been measured from these lines to that calculated from the hydrogen Hα-line at 656.27 nm which are in the same spectra under the same condition. Calibration curves were achieved for Si and Cu with linear regression coefficients about 0.99 and limits of detection values were 147 and 89 ppm respectively. Also, high accuracy linear relations have been obtained between Vickers mechanical hardness, the ratio between the Calcium ionic and neutral lines (Ca II/Ca I) and the plasma temperature. These results proved the importance of correcting the spectral intensity line for the self-absorption effect before the LOD measurement. Also, they confirmed the correction importance before evaluation of the hardness in LIBS experiments.

Optical emission spectroscopy for concrete strength evaluation utilizing calcium lines

Concrete is one of the most important materials in construction engineering. Evaluation of in-Situ concrete strength has become of great concern in construction process as well as for quality control. There are many destructive tests which can be conduct for the strength evaluation and for other performance parameters as well. However, load tests or core tests are not always possible or practicable. Since last decade, non-destructive testing has been widely accepted throughout the world in order to assess the quality of in-situ concrete. Compressive strength is considered as the most common measurement used by engineerings in design. The results of this test indicate if the concrete fulfills the requirements of the desired structure or not.In the present work, the laser-induced breakdown spectroscopy (LIBS) technique has been used as a diagnostic tool for the elemental composition of concrete and determination of the compressive strength. The ratio between the ionic calcium lines at 393.3 and 396.8 nm and the neutral line at 422.6 nm have been utilized to measure their compressive strength. These lines are reversible lines, as they are greatly self-absorbed. The self-absorption of calcium lines under investigation was corrected via comparison of the electron densities. These densities have been measured from calcium lines to that computed from the hydrogen Hα-line at 656.27 nm which are in the same spectra under the same state. A linear relationship has been obtained between compressive strength and the ratio of the calcium ionic to atomic spectral lines intensities (Ca II/Ca I). The results showed an acceptable with high accuracy linear relations.A new relation has been developed for comparison between compressive strength and the plasma temperature. The results reflect the importance of correcting the intensity of the emitted spectral line for the self-absorption effect before utilizing the compressive strength measurement in LIBS experiments. Also, it has been confirmed that the LIBS technique can be considered as a trustful semi nondestructive concrete strength test.

The RINGS Survey. III. Medium-resolution Hα Fabry–Pérot Kinematic Data Set

Abstract The distributions of stars, gas, and dark matter in disk galaxies provide important constraints on galaxy formation models, particularly on small spatial scales (&lt;1 kpc). We have designed the RSS Imaging spectroscopy Nearby Galaxy Survey (RINGS) to target a sample of 19 nearby spiral galaxies. For each of these galaxies, we obtain and model Hα and H i 21 cm spectroscopic data as well as multi-band photometric data. We intend to use these models to explore the underlying structure and evolution of these galaxies in a cosmological context, as well as whether the predictions of ΛCDM are consistent with the mass distributions of these galaxies. In this paper, we present spectroscopic imaging data for 14 of the RINGS galaxies observed with the medium spectral resolution Fabry–Pérot etalon on the Southern African Large Telescope. From these observations, we derive high spatial resolution line-of-sight velocity fields of the Hα line of excited hydrogen, as well as maps and azimuthally averaged profiles of the integrated Hα and [N ii] emission and oxygen abundances. We then model these kinematic maps with axisymmetric models, from which we extract rotation curves and projection geometries for these galaxies. We show that our derived rotation curves agree well with other determinations, and the similarity of the projection angles with those derived from our photometric images argues against these galaxies having intrinsically oval disks.

Optical emission and surface characterization of stainless steel treated by pulsed microwave-atmospheric helium plasma jet

A pulsed microwave-excited atmospheric pressure plasma jet MWAPPJ in helium, has been investigated by optical emission spectroscopy OES. Beside helium spectral lines various excited species such as atomic oxygen OI, hydrogen H α line, N2 + ion and nitrogen molecule species N2 (C3Πu) which are responsible for metal surface activation. The rotational T rot and vibrational temperature T vib were evaluated using optical emission spectroscopy and their dependences on the pulsed microwave parameters such as duty factor (20–70%) and a repetition rate (4 to 90 kHz) are investigated. Spectroscopic measurements show that, T rot, T vib and relative emission intensity of excited species greatly increases with increasing pulse duty factor. Meanwhile they show weak dependences as repetition frequency increased. Surface characterization of the examined stainless steel samples were performed through contact angle, Atomic force microscope AFM and X-ray photoelectron emission spectroscopy XPS. The contact angle decreased from 71° to 20° after pulsed MWAPPJ helium plasma at duty factor of 70% treatment for 30 s, which it is mainly due to incorporation of oxygen-containing functional groups as inferred from XPS results.

Spatial diagnostics of the laser-produced tin plasma in air

We present here new experimental studies on the laser-produced tin plasma generated by focusing the beam of a Q-switched Nd:YAG laser (532 nm) on the sample in air at atmospheric pressure. The optical emission spectra were recorded with a set of five spectrometers covering the spectral range from 200–720 nm. The electron temperature has been calculated to be about (10 600 ± 600) K using three methods; the two-line ratio, Boltzmann plot and the Saha–Boltzmann plot method, whereas the electron number density of about (9.0 ± 0.8) × 1016 cm−3 has been calculated using the Stark broadened line profiles of tin lines and the hydrogen Hα-line. Furthermore, the branching fractions have been deduced for 15 spectral lines of the 5p5d → 5p2 transition array in tin, whereas the absolute values of the transition probabilities have been calculated by combining the experimental branching fractions with the lifetimes of the excited levels. Our measured values are compared with those reported in the literature and NIST data base, showing good agreement.

Method of power density determination in microwave discharge, sustained in hydrogen–methane gas mixture

We present the results of studying a continuous microwave discharge maintained at a frequency of 2.45GHz in a CVD reactor based on a cylindrical resonator excited at the TM013 mode. The discharge was ignited in hydrogen and a gaseous mixture of hydrogen and methane and was studied by the method of optical emission spectroscopy. Density of atomic hydrogen and gas temperature were measured, as well as the spatial distribution of both optical emission intensity of the plasma and intensity of the Hα line of atomic hydrogen. The main parameters of the discharge were calculated numerically using the two-dimensional self-consistent model of the discharge. Basing on the obtained results, we proposed a method for high-precision experimental determination of the plasma volume and calculation of the specific energy contribution to the plasma, i.e., microwave power density in plasma (MWPD), with minimal errors. According to the calculations, in the experiment performed, the microwave power density in the plasma varied from 50 to 550W/cm3 as the gas pressure increased from 80 to 350Torr. The method allows one to perform unified MWPD calculations in different CVD reactors and to compare diamond film deposition regimes.

Self-Absorption Effects on Electron Temperature-Measurements Utilizing Laser Induced Breakdown Spectroscopy (LIBS)-Techniques

In the present work, we have studied the temporal evolution of aluminum alloy plasma produced by the fundamental (1064 nm) of a Q-switched Nd:YAG laser by placing the target material in air at atmospheric pressure. The four Al I-neutral lines at 308.21, 309.27, 394.40 and 369.15 nm as well as Al II-ionic lines at 281.61, 385.64 and 466.30 nm are used for the determination of the electron temperature Te using Saha-Boltzmann plot method. The neutral aluminum lines were found to suffer from optical thickness which manifested itself on the form of scattered points around the Saha-Boltzmann line. The isolated optically thin hydrogen Hα-line at 656.27 nm appeared in the spectra under the same experimental conditions was used to correct the Al I-lines which contained some optical thickness. The measurements were repeated at different delay times ranging from 1 to 5 μs. The comparison between the deduced electron temperatures from aluminum neutral lines before correction against the effect self-absorption to that after correction revealed a precise value in temperature. The results sure that, in case of the presence of self-absorption effect the temperature varies from (1.4067 - 1.2548 eV) as the delay time is varied from 0 to 5 μs. Whereas, in the case of repairing against the effect, it varies from (1.2826 - 0.8961 eV) for the same delay time variation.

NUMERICAL SIMULATIONS OF SPICULE ACCELERATION

Observations in the Hα line of hydrogen and the H and K lines of singly ionized calcium on the solar limb reveal the existence of structures with jet-like behavior, usually designated as spicules. The driving mechanism for such structures remains poorly understood. Sterling et al. shed some light on the problem mimicking reconnection events in the chromosphere with a one-dimensional code by injecting energy with different spatial and temporal distributions and tracing the thermodynamic evolution of the upper chromospheric plasma. They found three different classes of jets resulting from these injections. We follow their approach but improve the physical description by including non-LTE cooling in strong spectral lines and non-equilibrium hydrogen ionization. Increased cooling and conversion of injected energy into hydrogen ionization energy instead of thermal energy both lead to weaker jets and smaller final extent of the spicules compared with Sterling et al. In our simulations we find different behavior depending on the timescale for hydrogen ionization/recombination. Radiation-driven ionization fronts also form.

Measurements of Plasma Electron Temperature Utilizing Magnesium Lines Appeared in Laser Produced Aluminum Plasma in Air

We have utilized the relative intensity of magnesium lines originated from the Mg I at 285.2 nm and Mg II at 280.27, 279.55 nm to measure the plasma electron temperature. The plasma was produced via interaction of Nd:YAG laser with solid aluminum target contains traces of magnesium. The magnesium lines were found to suffer from optical thickness which manifests itself on the form of scattered points around the Saha-Boltzmann line. We have utilized a simple method used for rapid calculation to the amount of absorption to these lines via comparison of the electron densities as deduced from magnesium lines to that evaluated from the optically thin hydrogen Hα line at 656.27 nm appeared in the same spectra under the same condition. A correction to the magnesium spectral lines intensities was carried out; hence the corrected temperatures were re-evaluated. The measurements were repeated at different delay times ranging from 1 to 5 μsec. This work emphasizes on the importance of correcting the emitted spectral line intensity against the effect of self absorption before using them in the calculation of plasma electron temperature in laser induced breakdown spectroscopy (LIBS) experiments.