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, τ_l = 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 (T), electron number density (N), and plasma frequency (ʋ) have been increased. Furthermore, thermal beta (β_t) is also estimated analytically, and its value is smaller than one (β < 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.