Langdon effect in the realm of extreme ultraviolet source plasmas

Already some years ago, Langdon [Phys. Rev. Lett. 44, 575 (1980)] proposed that inverse bremsstrahlung absorption in plasmas drives free electrons into non-Maxwellian distributions. Radiation-hydrodynamic simulations of plasma-based light sources, however, often (implicitly) assume Maxwellian-distributed electrons. In this paper, we quantify the effect of non-Maxwellian distributions on laser absorption and thermal conduction in laser-driven plasma light sources. For irradiation conditions las⁢2
las∈[1011,1013]⁢Wcm−2µ⁢m2 and plasma parameters eff/∈[0.2,0.6]⁢eV−1, the electron distributions are predicted to be super-Gaussian of order ≃2.2–2.4. As a result, laser absorption is calculated to be 10–20% lower than plasmas with Maxwellian-distributed electrons. A ∼10–30% reduction of the Spitzer-Härm thermal conduction coefficient is also predicted.