New insights into the Langdon effect in extreme ultraviolet source plasmas

Jorge Gonzalez and John Sheil from ARCNL have published a paper in ‘Physical Review E’ that sheds new light on the Langdon effect in extreme ultraviolet (EUV) source plasmas. The paper gives theoretical evidence that electrons can be driven into non-equilibrium distributions (so-called non-Maxwellian distributions) in these plasmas, which is the first demonstration of its kind. This shows that one should be careful assuming that the electrons are in equilibrium in calculations. 

For plasmas in thermodynamic equilibrium, the velocity distribution of electrons follows a so-called Maxwellian distribution. A non-Maxwellian distribution is a generic term referring to any deviation from the equilibrium one. This study, titled “Langdon effect in the realm of extreme ultraviolet source plasmas,” explores the impact of non-Maxwellian electron distributions on laser absorption and thermal conduction in laser-driven plasma light sources. Researchers found a reduction of 10 to 20 percent in laser absorption in the case of non-Maxwellian distributions. 

The Langdon effect

Jorge Gonzalez, first author of the paper, says about the findings: “Our research highlights the necessity of incorporating the Langdon effect into EUV source simulations to enhance the accuracy of models. This could lead to more efficient and effective plasma-based light sources for various applications.” 

Impact on EUV source plasmas

John Sheil adds: “Understanding the impact of non-Maxwellian electron distribution functions on thermal transport and atomic kinetics in EUV source plasmas is crucial. Our work bridges important gaps in this area and sets the stage for future experimental validations.” 

This study highlights the need for experimental confirmation of non-Maxwellian electron distribution function (EDFs) in EUV source plasmas. Such experiments could provide new insights and validate the theoretical predictions, leading to further advancements in the field. 

Research implications

This publication is part of the ARIES project, funded by the Dutch Research Council (NWO) and conducted at ARCNL. For more details, you can access the full article.