Laser Induced Breakdown Spectroscopy from ns to fs laser pulses for the detection of deuterium in fusion plasma walls

Laser-Induced Breakdown Spectroscopy (LIBS) is a versatile technique for elemental analysis based on the emission from plasma generated by a focused laser pulse. This study aims to examine how laser energy, pulse width, delay time, and gas pressure affect the LIBS signal and spectral resolution for low-pressure detection of hydrogen and deuterium. Key objectives of our research are: use short laser pulses to “drill” well shaped craters in the sample; use small laser energy to increase depth resolution; minimize Stark broadening and enhance peak resolution, keeping a sufficient line intensity. Results indicate that increasing the delay time reduces spectral bandwidth but also decreases signal intensity. Higher gas pressures strengthen the signal but broaden spectral lines. Extending pulse duration from femtoseconds to nanoseconds produces longer-lasting and more intense signals, but with increased Stark broadening and lower resolution. These insights contribute to the optimization of LIBS for sensitive and high-resolution detection of light elements like hydrogen and deuterium at low pressure for plasma-facing wall analyses.