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 (${\mathrm{CH}}_2$O${)}_{\mathit{n}}$ capillaries. Electron densities (≲5×${10}^{19}$ ${\mathrm{cm}}^{\mathrm{-}3}$) and temperatures (≲50 eV) in the capillary were inferred by fitting axial, spatially integrated, time-gated spectra taken of O v i 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 i i i 3p-3d and C i v 3s-3p emission from inside the hollow anode were used to infer the presence of a cooler (${\mathit{T}}_{\mathit{e}}$≲25 eV), less dense (${\mathit{N}}_{\mathit{e}}$≲2×${10}^{18}$ ${\mathrm{cm}}^{\mathrm{-}3}$) plasma just outside the capillary.