Open AccessSimultaneous LIBS signal and plasma density measurement for quantitative insight into signal instability at elevated pressure
Author(s) -
Anil K. Patnaik,
Yue Wu,
Paul S. Hsu,
Mark Gragston,
Zhili Zhang,
James R. Gord,
Sukesh Roy
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.025750
Subject(s) - laser induced breakdown spectroscopy , signal (programming language) , instability , materials science , plasma , laser , electron density , spectroscopy , electron , atomic physics , ultrashort pulse , optics , physics , quantum mechanics , computer science , mechanics , programming language
Laser-induced breakdown spectroscopy (LIBS) evaluates the emission spectra of ions, radicals, and atoms generated from the breakdown of molecules by the incident laser; however, the LIBS signal is unstable at elevated pressures. To understand the cause of the signal instability, we perform simultaneous time-resolved measurements of the electron density and LIBS emission signal for nitrogen (568 nm) and hydrogen (656 nm) at high pressure (up to 11 bars). From correlations between the LIBS signal and electron number density, we find that the uncontrollable generation of excess electrons at high pressure causes high instability in the high-pressure LIBS signal. A possible method using ultrafast lasers is proposed to circumvent the uncontrolled electron generation and improve signal stability at high pressure.