Spectroscopic investigation of the RGS-II hypervelocity plasma armature

A spectroscopic investigation of the plasma armature in the railgun simulator RGS-II is underway. RGS-II can accelerate the plasma armature to velocities up to 20 km/s and produce armature currents up to 300 kA. The optical signal is extracted at the midbore position by a fiber-optic bundle. Emission spectra are recorded by an optical multichannel analyzer system. The emission spectra are used to identify the plasma constituents. Relative intensities of neutral and ionic species are correlated with interferometric measurements of the electron density to estimate the plasma temperature using the Saha equations. Effects of the ambient chamber pressure and total armature current on the plasma armature are being studied over a range of 200 mtorr to atmospheric pressure and from 50 to 300 kA, respectively.<>