Characterization of a Laser Ablation Impurity Injector for the Tokamak de Varennes

A laser ablation impurity injector has been designed for use on the Centre Canadien de Fusion Magnétique Tokamak de Varennes. A method using nuclear activation analysis of ablation-exposed targets has been developed to measure the exact quantities and spatial distribution of the injected particles. Combined with time-of-flight velocity measurements, the injector has been characterized in terms of laser energy fluence, ablated material, film thickness, and background gas pressure. Three distinct populations of ablated material (atoms, molecular clusters, and micron-sized liquid droplets) have been identified and studied.