Efficiency evaluation of fuel retention diagnostic in first wall by LID-QMS: Based on LIBS

Quantifying deuterium (D) retention in plasma-facing components (PFCs) with minimal material impact is critical for fusion reactor operation. This study employs laser-induced desorption coupled with quadrupole mass spectrometry (LID-QMS) for in situ D-retention analysis on HL-3 graphite tiles. As an auxiliary strategy, laser-induced breakdown spectroscopy (LIBS) is implemented under optimized low-fluence conditions to intermittently evaluate LID-QMS desorption efficiency during operation. Laboratory experiments demonstrate > 80 % deuterium release in the first LID pulse (laser fluence > 570 MW/m²), validated via cross-calibrated QMS measurements; LIBS provides rapid efficiency assessment by correlating D/H spectral results with QMS-resolved H, HD and D₂ desorption signals. The integrated LID-QMS-LIBS framework permits: real-time optimization of LID parameters during material analysis, direct efficiency validation without destructive sampling. This methodology is currently being implemented on HL-3 tokamak for in situ wall-D monitoring, demonstrating potential to replace ex situ post-mortem analysis in future fusion devices.