Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement

Abstract

He, X. N.; Li, C. M.; Zhou, Y. S.; Cai, Z. X.; Zeng, X. Y.; and Lu, Yongfeng, "Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement" (2011 Abstract: To enhance optical emission in laser-induced breakdown spectroscopy, both a pair of permanent magnets and an aluminum hemispherical cavity (diameter: 11.1 mm) were used simultaneously to magnetically and spatially confine plasmas produced by a KrF excimer laser in air from pure metal and alloyed samples. High enhancement factors of about 22 and 24 in the emission intensity of Co and Cr lines were acquired at a laser fluence of 6.2 J/cm 2 using the combined confinement, while enhancement factors of only about 11 and 12 were obtained just with a cavity. The mechanism of enhanced optical emission by combined confinement, including shock wave in the presence of a magnetic field, is discussed. The Si plasmas, however, were not influenced by the presence of magnets as Si is hard to ablate and ionize and hence has less free electrons and positive ions. Images of the laser-induced Cr and Si plasmas show the difference between pure metallic and semiconductor materials in the presence of both a cavity and magnets.

Accuracy improvement of quantitative analysis by spatial confinement in laser-induced breakdown spectroscopy

“…Popov et al reported the confinement effect of plasmas created in a small capped cylindrical chamber whose size was 4 mm by 4 mm, improved the limit of detection (LOD) by two to five times for different elements [24,25]. Our previous research also showed the enhancement of plasmas confined with an aluminum hemispherical cavity, resulting in an enhancement factor of 12 for Mn lines in a substrate with a low Mn concentration [26,27]. Wang et al fabricated a polytetrafluoroethylene (PTFE) plate of 1.5 mm thick with a diameter of 3 mm to regularize coal plasma.…”

“…The plasma was compressed and become uniform; therefore, the spectral line intensity was enhanced. As a result, the accuracy of quantitative analysis was improved [27,28].…”

Effects of a static inhomogeneous magnetic field acting on a laser-produced carbon plasma plume

“…Early investigations focused on measurements of plasma parameters and in the identification of magnetic field induced kinetic effects on plasma behavior. [6][7][8] Later, several investigations on laser plasma dynamics in sub-Tesla static magnetic fields have been reported, aiming to improve plasma confinement in pulsed laser deposition (PLD) processes, 9,10 to enhance plasma emission in laser induced breakdown spectroscopy (LIBS), [11][12][13] to increase the ion yield and beam current in laser ion sources (LIS), 14 or to get insight in interpreting data related to astrophysical observations, 15,16 among others. In this context we report on a series of experiments aiming to unveil further details of the interaction between the laser produced plasma and a static axial magnetic field.…”

Metal Identification Based on Laser-induced Breakdown Spectroscopy and BP Neural Network

“…Guo Lianbo [4],etc., for example, the support vector machine algorithm assisted laser induced breakdown spectroscopy research of qualitative identification technology for a variety of plastic. Although he has performed well in such studies, but did not involve the classification of scrap metal in.…”