Development of an ablation measurement technique using plasma armatures

Summary form only given. A novel technique is being developed to measure the ablation threshold and ablation rate of electrical insulators. Ablation is the loss of material due to incident thermal energy. Ablation thresholds and rates are important parameters for evaluating a material´s suitability for a variety of high temperature applications, from high-current switches to fusion reactor inner walls. These measurements are accomplished using a plasma armature railgun containing gun walls fabricated from the test material. Ablation parameters may be determined by measuring the arc´s velocity as a function of armature current and background gas pressure. Preliminary experiments have been performed on Lexan and Mullite. The data identified the onset of ablation in Mullite and provided a relative comparison of their ablation rates. This technique may provide an important tool for assessing the suitability of electrically insulating materials for variety of high temperature applications.