Spectroscopic measurements of electron density and temperature in polyacetal-capillary-discharge plasmas

Spectroscopic measurements were made of electron density and temperature histories in plasmas formed by 80-ns risetime, 6--16-kA peak current, pulsed discharges in 0.5- and 1-mm diameter, 1-cm-long polyacetal (CH₂O)ₙ capillaries. Electron densities ({}5×{}10¹⁹ cm^-3) and temperatures ({}50 eV) in the capillary were inferred by fitting axial, spatially integrated, time-gated spectra taken of O vi 3p-4d and 3d-4f emission with theoretical Stark-broadened profiles that were corrected for optical-depth effects. Off-axis (at 45^∘{} to the capillary axis) time-gated spectra taken of C iii 3p-3d and C iv 3s-3p emission from inside the hollow anode were used to infer the presence of a cooler (Tₑ{}25 eV), less dense (Nₑ{}2×{}10¹⁸ cm^-3) plasma just outside the capillary.