The electron density and temperature of the laser induced silicon plasma were measured using two different methods. The plasma was produced via the interaction of high peak power Nd-YAG laser at the fundamental wavelength of 1064 nm with a plane solid iron target contain small traces of silicon as an element of minor concentration. The lines from the Si I at 288.15 nm and Si II-ionic lines at 413.08 and 634.71 nm were utilized to evaluate the plasma parameters. The reference plasma parameters were measured utilizing the Hα-line at 656.27 nm appeared in the spectra under the same condition. The electron density was measured utilizing the Stark broadening of the silicon lines and the temperature from the standard Saha-Boltzmann plot method. The comparison between electron densities from different silicon lines to that from the Hα-line reveals that the Si I-line at 288.15 nm contain some optical thickness while the Si II-ionic lines were found to be free from this effect. The measurements were repeated at different delay times between the laser and the camera in the range from 1 - 5 μsec. The electron density was found decreases from 2 × 10¹⁸ down to 4 × 10¹⁷ cm^–3. After correcting the spectral intensity at the Si I-line at 288.15 nm, the temperatures evaluated from the different methods were found in an excellent agreement and decreases from 1.25 down to 0.95 eV with delay time

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 H α 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.

A Software program has been developed in order to perform a fast and reliable calculation to plasma electron density in laser induced breakdown spectroscopy (LIBS) experiments. This program is based on analyzing the emitted spectral line shape via utilizing facilities of the MatLab7^? package to perform this task. This software can perform the following tasks; read the exported data file (^*txt-format) from ICCD camera-software, specify the working wavelength of interest, removes the continuum emission component appeared under the line, calculates the spectral line intensity of the line, calculates the spectral shift of the line from the tabulated values, correct against spectral shift jitter at the peak emission, de-convoluting and extracting the different components contributing to the emitted line full width at half of the maximum (FWHM) and finally calculates the plasma electron density. In this article we shall present the results of the test measurement of the plasma electron density utilizing spectral line shape analysis to the emitted H<i>_α</i>-line, Si I-line at 288.15 nm and O I-line at 777.2 nm at different camera delay times ranging from 1 to 5 μs