Magnetic field confined laser-induced plasma: Improvement in sensitivity and repeatability

In this work, the transverse magnetic field confined laser-induced breakdown spectroscopy (MC-LIBS) technique was applied to investigate the signal sensitivity and repeatability of Al alloy plasma in the specially designed assembly. The emission signals from laser-induced plasma were recorded with varying laser energy (80 to 160 mJ) and magnetic field strength (1 to 3.5 kG). An emission signal enhancement up to 7 times was observed at 140 mJ laser energy and at 3 kG magnetic field strength. Compared to conventional LIBS, the magnetic field confined-LIBS improved the signal-to-noise ratio (SNR) by up to 5 times and the detection limit (LOD) from 86 to 26 ppm for zinc emission lines. Repeatability was evaluated using the relative standard deviation (RSD) of the Mg and Si emission lines, which was improved from 23 to 12% and 25 to 14%, respectively. Similarly, the measurement-to-measurement RSDs in electron temperature (Te) and electron number density (Ne) were improved from 12 to 7% and 1 3 to 5% when compared with conventional LIBS.