Ablation measurements on EML insulators using free-arcs

A new technique has been used to determine the ablation threshold and ablation rate of EML materials. Analysis of experimental data obtained by measuring free-arc velocity as a function of rail current in the presence of a background gas has been performed. A simulation of the free-arc motion has been developed using the graphical programming capabilities of LabVIEW. Nonablating theoretical data have been calculated from the free-arc model and have been used to identify the onset of ablation in the experimental data. Likewise, for the ablating case, the ablation coefficient can be extracted from the experimental data using system sensitivity and parameter identification methods. Ablation measurements were made on Lexan and mullite insulators. The ablation coefficients and ablation thresholds obtained indicate that Lexan ablates more significantly and has a lower ablation threshold than mullite, as expected.