Experimental and numerical investigations on the density profile of CO2 laser-produced Sn plasma for an EUVL source

Experimentally observed density profile of CO 2 laser-produced Sn plasma was compared with that predicted by one dimensional hydrodynamic radiation numerical code. Experimental data showed a much smaller corona and a much shorter shift distance of the critical density from the initial target surface as compared with those predicted by an isothermal model and the numerical simulation. The possible reason may come from thin localized laser deposition region, less energy transport into the corona and into the dense region beyond the critical density. This research suggests that more efforts to understand the fundamental dominating the interaction of CO 2 laser with high Z plasma are necessary to form a more solid foundation for the application of numerical method to the development of the EUVL source.