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

Abstract

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 (${\mathrm{CH}}_{2}$O${)}_{\mathit{n}}$ capillaries. Electron densities (\ensuremath{\lesssim}5\ifmmode\times\else\texttimes\fi{}${10}^{19}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) and temperatures (\ensuremath{\lesssim}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\ifmmode^\circ\else\textdegree\fi{} 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 (${\mathit{T}}_{\mathit{e}}$\ensuremath{\lesssim}25 eV), less dense (${\mathit{N}}_{\mathit{e}}$\ensuremath{\lesssim}2\ifmmode\times\else\texttimes\fi{}${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) plasma just outside the capillary.