Numerical study of DP-LPP: Effects of laser wavelength and external magnetic fields on absorption of the main laser pulse

Dual-pulse laser-driven plasmas are widely utilized in lithography to enhance the conversion efficiency (CE) of extreme ultraviolet radiation. We employed the radiation magnetohydrodynamics code FLASH to model laser-plasma interaction dynamics across different magnetic fields and main-pulse laser wavelengths. The interaction between main pulse lasers with wavelengths from 1 to 10 μm and pre-plasma was analyzed, and the results reveal a strong wavelength-dependent behavior in the energy deposition of lasers within pre-plasma. The variations in energy deposition efficiency and CE are primarily attributed to the differences in the regions where lasers of varying wavelengths deposit their energy. The application of an external magnetic field perpendicular to the laser incidence direction constrains plasma expansion, forming a high-density shell. Interaction between the main pulse and this shell-like pre-plasma generates electron densities exceeding the critical threshold, shifting the energy propagation mode from penetration to reflection and significantly altering its energy deposition efficiency.