Optical emission spectroscopy of plasma streams in PF-1000 experiments

The optical spectroscopy in the visible range was used to determine properties of the dense magnetized plasma generated in the PF-1000, a 1 MJ plasma focus device operating in the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw, Poland. The experiments were performed in a vacuum chamber pumped out to the basic pressure of 2 x 10(-5) hPa. The initial pressure of the pure deuterium filling was 2.9 hPa, while that of the deuterium-argon mixture was 1.07 hPa of D(2) and 0.13 hPa of Ar. The deuterium-plasma emission contained the Balmer series (D(alpha) D(beta) and D(gamma)) and a few distinct copper (Cu I) lines originating from the inner electrode material. The emission of the deuterium-argon plasma was rich in Ar II lines. The electron density (n(e)), averaged over line of sight, of order of 10(16) cm(-3) was calculated on the basis of the D(beta) and D(gamma) emission only, because the 13 line was strongly self-absorbed. A group of the Ar II spectral lines was used to estimate the excitation temperature (T(exc) = 3 eV) by means of a Boltzmann plot. Additionally, the temporal evolution of the electron density was determined on basis of the Stark broadening of the D(beta) and D(gamma) lines.