Rail and insulator spectra from plasma railgun armatures

Summary form only given, as follows. High-resolution radiation spectra of the plasma armature in a railgun have been recorded in the rail and insulator simultaneously, at the same axial location, using optical multichannel analyzers and 1-mm quartz fibers. The spectra have been obtained at approximately 6 mm and 24 mm from the leading edge of the armature, which correspond to the increasing current and peak current parts of the plasma armature, respectively. The gate width was 1 mu s, resulting in a spatial resolution of about 1.5 mm. The rail emission signal follows the armature current profile very closely, while the radiation through the insulator side is partially blocked due to ablation products in the insulator boundary layer. Resonance absorption lines of AlI, CuI, and CaII have been identified along with possible traces of carbon and nitrogen compounds. A detailed radiation model has been used to estimate the plasma centerline temperature, the temperature profile, and the plasma composition.<>