Abstract: Debris from laser produced plasma（LPP）severely decreases the lifetime of extreme ultraviolet optics. In order to alleviate the effect of debris in extreme ultraviolet（EUV），the effects of an external magnetic field on the expansion dynamics of Sn plasma have been investigated with a Nd：YAG laser. The characteristics of ions from Sn plasma，optical emission spectrum and the EUV emission have been studied by comparing with and without the effect of magnetic field. The results show the effectively reduction in the ion kinetic energies of the plume species with a modest magnetic field of 0. 6 T. The emission shows significant enhancements of the spectral lines. The enhancement of 2.5 times in the electron density is obtained in the presence of the magnetic field. The results also indicate that the EUV emission do not depend significantly on the effect of magnetic field.

Key words: laser-produced plasma, magnetic field, debris, electron density