Improving the spectral intensity of aluminum plasma by applied-magnetic field in laser-induced breakdown spectroscopy

Abstract

In this report, an impact of applied-magnetic field on laser induced breakdown spectroscopy (LIBS) emission with different air pressures and several time delays was explored by analyzing the solid aluminum (Al) sample. A Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at its basic wavelength (1064 nm) was utilized to generate the plasma and its optical emission was recorded with the help of an optical emission spectroscopy (OES) technique. A notable improvement was observed primarily at low pressure and shorter delay time for Al atomic lines due to the effect of magnetic field (0.5 T). For the air pressure of 100 Pa and delay time of 100 ns, the signal enhancement of approximately 2-fold was obtained for Al (I) 396.1 nm spectral line. The signal enhancement due to the magnetic confinement was attributed to an increase in electron-impact excitation rate and recombination processes. The plasma parameters like, electron temperature (Te) and electron number density (ne) were also affected under the applications of magnetic field. A considerable enhancement was noticed in comparison to the field-free case. The plasma temperature attained their highest values at 500 Pa only, however, the electron density was found to be completely enhanced across the magnetic field. The optical enhancement is accredited to the plasma-confinement by applied field and has scope in improving the LIBS sensitivity.