Electron density of the prepinched phase of a cerium (Z=58) vacuum spark plasma obtained from line emission measurements around 1 keV

Time-integrated space-resolved spectra emitted from vacuum spark cerium plasmas have been recorded in the 10-15 Å range. Photometric calibration of the spectrograph components, i.e., the RbAP crystal, a noise blocking filter, and the Kodak SC5 photographic plates used to record the spectra, made possible an estimate of absolute brightnesses of individual lines. The electron density of the emitting plasma has been evaluated, comparing experimental line ratios with those predicted by a density-dependent collisional-radiative model in which optical depth effects have been included. The conclusions of the present work are that the emitting plasma dimension is 200-500 μm and the electron density of this region is in the range 7×10¹⁹ -3×10²⁰ cm^-3.