Characterization of Laser Produced Plasmas in Different Initial Configurations and Expanding in Neutral and Ionized Gas Backgrounds

Experimental studies of the dynamics and properties of laser produced plasmas in different initial configurations, using a Titanium target and a Nitrogen background, are presented. First, an annular plasma, produced by focusing a 5 ns laser beam using a combination of axicon prism and convergent lens and expanding in neutral Nitrogen background, in the range 50-2000 mTorr, is characterized using 30 ps simultaneous Mach-Zehnder interferometry, shadowgraph and schlieren imaging. Second, a plasma plume, produced by point focusing of a 4.8 ns laser beam and expanding in 50-1000 mTorr Nitrogen background, either neutral or in a RF produced plasma, is characterized with 4 ns Mach-Zehnder interferometry. Detailed time resolved measurements of the plasma density, as a result of Abel inversion of the interferograms, with characteristic plasma densities ~5×10 15 -1×10 17 cm -3, , and plasma dynamics resulting from shadowgraph and schlieren imaging, will be presented and discussed.