Al plasma jet formation via ion stream compression by surrounding low-Z plasma envelope

Abstract

In our earlier papers it was demonstrated that the plasma pressure decreases with the growing atomic number of the target material. In this context a question arose about the possibility to collimate the Al plasma outflow by using the plastic plasma as a compressor. For that purpose a plastic target with an Al cylindrical insert of 400 μm in diameter was used. The experiment was carried out at the PALS laser facility. The laser provided a 250 ps (FWHM) pulse with the energy of 130 J at the third harmonic frequency (λ3 = 0.438 μm). The focal spot diameters (ΦL) 800, 1000, and 1200 μm ensured predominance of the plastic plasma, its transversal extension being large enough for the effective Al plasma compression. To study the Al plasma stream propagation and its interaction with the plastic plasma, a 3-frame interferometric system and 4-frame x-ray camera were used. The information on distribution of electron temperature in the outflowing Al plasma was provided by x-ray spectroscopy. The experimental results reported in the paper are discussed by virtue of a simple theoretical analysis.