[8a-S5-1~11] 3.6 Laser processing

10:15 AM - 10:30 AM JST(1:15 AM - 1:30 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[8a-S5-6] Generation Conditions of Nanosecond-Pulsed Laser-Induced Plasma in a Supercritical CO2

〇Riku Minato¹, Yusuke Yasuda¹, Hitoshi Muneoka^1,2, Kazuo Terashima¹, Tsuyohito Ito¹ (1.The Univ. of Tokyo, 2.Tohoku Univ.)

Keywords:

laser-induced breakdown,supercritical fluid,nanosecond-pulse laser

Laser-induced breakdown plasma is an important reaction field for laser processing, including nanoparticle synthesis and thin-film formation. In this study, nanosecond laser-induced breakdown in CO2 was investigated from high-pressure gas to supercritical conditions by continuously varying the medium density. Breakdown probabilities were measured shot by shot using 1064 nm and 532 nm Nd laser irradiation, and the 50% breakdown energy was defined as the threshold. The threshold decreased with increasing density and showed general agreement with a previously reported density-scaling law, indicating that breakdown in supercritical CO2 can be largely understood as an extension of density effects observed in gases, liquids, and solids. However, the density dependence differed between wavelengths, and a local decrease in breakdown probability was observed near the critical point, suggesting that density fluctuations can affect nanosecond laser-induced breakdown.