Thermal Conduction in Laser‐Driven Tin Plasmas and the Sensitivity of Plasma Properties to the Flux Limiter

We study the role of thermal conduction in laser-produced tin plasma sources of extreme ultraviolet (EUV) light using radiation-hydrodynamic simulations. Adopting the flux-limited Spitzer–Härm approach, we investigate the sensitivity of the electron temperature, electron density, net in-band emissivity, and conversion efficiency to the choice of flux limiter for plasmas driven by two laser wavelengths: laser = 10.6 and 2 μm. For plasmas driven by laser = 10.6 μm laser light, the plasma properties are highly sensitive to flux limiters in the range 0.01 ≤ ≤ 0.2, which originates from the choice of heat flux (either Spitzer–Härm or free-streaming) adopted in the simulations. The conversion efficiency is found to increase sharply from 2% to 5% with increasing in this range owing to the increased population of EUV-emitting charge states in the plasma. By quantifying the Knudsen number, we find that SH theory is not valid in the underdense corona in these plasmas. Plasmas driven by 2 μm-wavelength lasers are, on the contrary, largely insensitive to the choice of given the higher electron densities and dominance of the free-streaming heat flux. We find that Spitzer–Härm theory is valid in these plasmas.

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