Improvement of spectral intensity and resolution with fiber laser for on-stream slurry analysis in laser-induced breakdown spectroscopy

It is still challenging to apply laser-induced breakdown spectroscopy (LIBS) to slurry on-stream analysis due to the moisture in slurry samples causing the low spectral intensity. In this work, a high-frequency pulsed fiber laser was proposed to quickly remove the moisture in slurry samples at the detection point for the first time. The spectral emission intensity and line broadening due Stark effect were investigated for the dual-pulse of fiber laser assisted LIBS (FL-LIBS) mode and signal-pulse LIBS (SP-LIBS) mode. It found that the spectral intensities of Fe and Ca elements were enhanced, while the matrix elements of H and O elements were decreased. Moreover, the currently available spectroscopic diagnostics of plasma, such Boltzmann plot have been used to measure the plasma temperature, while the hydrogen line broadening have been used in the characterization of electron densities. It reveals the type of higher-temperature and lower-density plasma was obtained. The experimental results demonstrated that the fiber laser had the potential to improve LIBS signal intensity and spectral resolution for aqueous matrix samples.