Development of LIBS Methodologies for Fusion-Relevant Materials Analysis

Laser-Induced Breakdown Spectroscopy (LIBS) is a promising diagnostic technique for hydrogen isotope detection in fusion-relevant materials; however, reliable separation of the hydrogen (Hα) and deuterium (Dα) emission lines is limited by strong spectral broadening and the short lifetime of the emitting plasma. The main objective of this thesis was to reduce emission linewidths and improve LIBS methodologies to enable clear Hα–Dα discrimination. A dedicated LIBS laboratory was established, integrating nanosecond, picosecond, and femtosecond laser systems, ICCD-based spectrographs, vacuum and gas-handling infrastructure, and electrical discharge assemblies. LIBS parameters were locally optimised with respect to laser pulse duration, energy, ambient pressure, gate delay, and gate width. The results show that high signal intensity alone is insufficient for isotope separation; instead, early-time detection under low-broadening conditions is critical. Picosecond LIBS at reduced energy and pressure improved spectral resolution compared to nanosecond excitation, while femtosecond LIBS provided the cleanest spectra due to rapid plasma expansion and suppressed Stark broadening. A comprehensive crater morphology study was performed on tungsten and molybdenum using optical profilometry. Ultrashort laser pulses produced well-defined, reproducible craters with minimal thermal effects. This behavior enabled estimation of material removal per shot and allowed depth profiling. Discharge-assisted LIBS was investigated to enhance signal intensity and stability without increasing linewidth. Glow-discharge operation at reduced pressure sustained excitation after plume decay, enabling long integration times and mitigating signal degradation. In the final phase, deuterated molybdenum samples were prepared by low-pressure electrical discharge, yielding laboratory-prepared surfaces that are far from real treated samples; however, they can be used to test Dα and Hα simultaneously. Optimized femtosecond LIBS measurements demonstrated the separation of Hα and Dα lines. Overall, this work establishes a robust experimental framework for high-resolution, depth-resolved hydrogen isotope diagnostics, with direct relevance to fusion research and plasma material interaction studies