A copper helical coil antenna was developed, characterized, and optimized for 2.45 GHz operations supplied by a microwave semiconductor oscillator. The application field of interest is laser-induced breakdown spectroscopy enhanced by microwave. Simulations using the Ansys HFSS demonstrate the superior localized E-field strength of the helical coil antenna, compared with other antenna-type structures. Simulation results show that E-field strength at the tip of the antenna has a logarithmic trend for increasing the coil pitch. The optimum pitch is 5 mm for a coil diameter of 6.5 mm upon consideration of the system compactness. Despite the antenna’s open-circuit end, the presence of target samples does not interfere with the E-field and H-field distribution of the antenna and the surrounding environment. Applications in microwave-enhanced laser-induced breakdown spectroscopy (MWLIBS) confirm the importance of the antenna reflector. The electric field strength was over 100 times higher than the previous capacitor-like antenna. The antenna configuration angle was then experimentally optimized for maximum enhancement effects in the spectrochemical analysis of Al₂O₃. The antenna angle of 60° from the laser beam propagation achieved maximum enhancement in the emission signal of Al I.

The detection of chloride in reinforced concrete, crucial for maintenance against damage from de-icing salt or seawater, is advanced by Laser-Induced Breakdown Spectroscopy (LIBS). This study demonstrates that integrating microwaves with LIBS enhances cement analysis, improving the signal-to-noise ratio by up to four times and extending the detection limit for chlorine to 0.17 ± 0.02 wt%. As a method, microwave-enhanced LIBS (MWE-LIBS) has existed for a decade, but in cement analysis, MWE-LIBS has been used for the first time in Cl I atomic emission measurements. This pioneering approach provides a more efficient alternative, marking a significant advancement in cement analysis.

This study highlights the impact of microwaves in laser-induced breakdown spectroscopy, yielding vital implications for plasma analysis and spectroscopy.

Utilizing microlasers and microwaves, our study examined the impact of microwaves on the expansion of air plasma. We applied microwaves to the air plasma generated by a microlaser, visualized its growth using a phone camera, and recorded plasma emissions using a high-resolution spectrometer. Software tools were then used to analyze these emissions for temperature changes and electron density. Notably, we noticed a 400-fold increase in plasma volume due to microwave enhancement, even though the microlaser operated at a modest energy level of 1 mJ. Simultaneously, we recorded an increase in temperature and a decrease in electron density when the plasma was subjected to microwaves, indicative of nonequilibrium plasmas. Further, a minor shift in electron temperature during microwave exposure pointed toward the ability of microwaves to sustain plasma characteristics over time. These findings suggest that the microwave application potentially improves the analytical performance of laser-induced breakdown spectroscopy.