Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

The temporal and spatial evolution of electron temperature and electron density from Sn plasma produced by a CO2 laser has been investigated in vacuum using spectroscopic methods. The plasma parameters were inferred by the Boltzmann plot method from experimentally observed line profiles of singly ionized Sn and Stark broadened profiles. At a laser intensity of 1010 W/cm2, electron temperature and density were measured to be within 1.13 eV to 0.53 eV and 5.3×1016 cm−3 to 1.4×1016 cm−3, respectively, for delay times between 200 ns and 1100 ns, and at distances up to 5 mm along the target normal. The results show the electron temperature and density from Sn plasma produced by a CO2 laser with wavelength of 10.6 μm to be lower than previously reported results using a 1064 nm laser in a similar parameter regime. The lower temperature in the region far away from the target surface confirms the smaller interaction region for CO2 laser as compared with that of neodymium-doped yttrium aluminum garnet laser.