Magnetic-Field-Confined Laser Induced Kohl Plasma: Elemental Analysis and Plasma Characterization.

In this study, the laser-induced kohl plasma is produced in the vicinity of the transverse magnetic field (B) of 0.8 T. A Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) pulse laser (λ = 1064 nm, E = 100 mJ, τl = 8 ns) is focused to produce the kohl plasma with and without a B, and the plasma emissions are recorded using a laser-induced breakdown spectroscopy (LIBS) spectrometer. The comparison of the emission spectra shows that most of the emission line intensities are reduced due to the field. However, except for a few lines which are enhanced up to three times. However, the plasma parameters such as electron temperature (Te), electron number density (Ne), and plasma frequency (ʋp) have been increased. Furthermore, thermal beta (ßt) is also estimated analytically, and its value is smaller than one (ß < 1) for all samples, which confirmed the evidence of magnetic confinement effects. According to the analysis of the kohl emission spectrum, several elements were detected (Pb, Ca, Mg, Fe, Cr, and Zn), among which lead (Pb) and chromium (Cr) may cause chronic health effects like contact dermatitis and neurological diseases. A calibration-free LIBS (CF-LIBS) method is used for the quantitative elemental analysis of the detected elements, which yields Pb as 15-74% and Cr as 3%, which exceed the permissible limit for kohl.

Effects of wall shear stress on unsteady MHD conjugate flow in a porous medium with ramped wall temperature.

This study investigates the effects of an arbitrary wall shear stress on unsteady magnetohydrodynamic (MHD) flow of a Newtonian fluid with conjugate effects of heat and mass transfer. The fluid is considered in a porous medium over a vertical plate with ramped temperature. The influence of thermal radiation in the energy equations is also considered. The coupled partial differential equations governing the flow are solved by using the Laplace transform technique. Exact solutions for velocity and temperature in case of both ramped and constant wall temperature as well as for concentration are obtained. It is found that velocity solutions are more general and can produce a huge number of exact solutions correlative to various fluid motions. Graphical results are provided for various embedded flow parameters and discussed in details.