Plasma ion emission enhancements of Zr using microwave-enhanced laser-induced breakdown spectroscopy

Abstract

In nuclear debris decommissioning, remote analysis using laser-induced breakdown spectroscopy (LIBS) guarantees the in-situ measurement of nuclear fuel debris inside the unit core. For nuclear fuel debris analysis, the detailed ion emission of Zr is essential owing to the proximity of the emission lines to U isotopes. In this study, Zr ion emissions were analyzed using microwave-enhanced LIBS with microlasers and standard yttrium aluminum garnet (YAG) lasers at different laser wavelengths (1064 nm and 532 nm). When the microwave expanded the microlaser-produced plume, the plasma emission and signal-to-noise ratio (SNR) enhancement were sustained for more than 1.0 ms, allowing analysis of ion emission. The results showed that ion emission was sustained by microwaves at the same rate as atomic emission. The ionization effects of microwaves on the LIBS analysis were revealed in the high-resolution spectrum measurements with resolving powers of 50,000–150,000. The enhancement coefficient, SNR, and intensity ratio Zr II/Zr I confirmed enhanced ionization using microwaves. At shorter laser wavelengths, microwaves suggestively increased ion emissions.