UC San Diego

It was found that the electron density scale length of Sn plasma irradiated with a long duration CO2 laser pulse is much shorter than that predicted by the classical isothermal model. The experimentally observed small dominant region of in-band (2% bandwidth) 13.5-nm extreme ultraviolet (EUV) emission coincides with this constrained hydrodynamic behavior. The lower hydrodynamic efficiency may come from the strongly inhibited ablation mass and makes a CO2-laser-produced Sn plasma suitable as an EUV radiation source.