Time- and space-resolved spectroscopic characterization of a laser carbon plasma plume in an argon background

We present time- and space-resolved spectroscopic observations of a laser-produced carbon plasma, in an argon background. An Nd:YAG laser pulse, 370mJ, 3.5ns, at 1.06m, with a fluence of 6.9Jcm ², is used to produce a plasma from a solid graphite target in a 0.5 to 415mTorr argon background. The spectral emission in the visible is recorded with 15ns time resolution. We use 20ns time resolution plasma imaging, filtered at characteristic carbon species emission wavelengths, to study the dynamics of the expanding plasma. The carbon plasma emission is found to evolve from the characteristic of single ionized carbon, to a more complex one, where C ₂ and C ₃ molecular bands dominate. Several plasma fronts, with either ionic or molecular composition, are seen to detach from the laser target plasma. The temporal and spatial features of the molecular carbon species evolution are found to be dependent on the actual argon background pressure.