Studies of Pulsed Plasma-Ion Streams During Their Free Propagation And Interaction With Carbon-Tungsten Targets In PF-1000 Facility

The paper presents results of recent experimental studies within the PF-1000 plasma-focus facility [1], which were performed during the free propagation of pulsed plasma-ion streams inside the vacuum chamber, and during their interaction with different targets. Optical spectra were recorder by means of a Mechelle registered 900 spectrometer operated with some delays in relation to the discharge current peculiarity (dip) and with exposition varied from 100 ns to 100 μs. The recorded spectral lines were used to estimate the density of the free-propagating plasma stream. The electron concentration, as estimated from the Stark broadening of the Dβ line recorded at a distance of z = 30 cm from the electrode ends, changed from about 4x1017 cm-3 to 2x1016 cm-3 in about 30 μs. Analogous spectroscopic measurements were carried out in experiments performed with targets made of carbon and sintered tungsten, which were placed at a distance of 15 cm from the electrode outlet, where q = 1010 W/cm2, and at a distance of 30 cm, where q = 109 W/cm2. Particular attention was paid to investigation of a plasma layer formed in the front of the target. In that case the electron density, as estimated on the basis of carbon-and deuterium-ion lines, changed from about 3x1018 cm-3 to 3x1016 cm-3 in 30 μs. For the target made of the sintered tungsten, which was placed at a distance of 30 cm, the recorded optical spectr a showed intense Dα and Dβ lines as well as CII-CIV lines, which covered tungsten (WI and WII) lines