Simulation of Tin Plasmas & Theory of Laser Light Absorption

An investigation of the physical properties of tin plasmas, motivated by nanolithography. This work concerns a novel method of generating extreme ultraviolet (EUV) light from a laser-produced plasma. In particular, we consider the irradiation of a tin microdroplet with a single laser pulse from a 2 micron wavelength laser, as opposed to the state-of-the-art pre-pulse–main pulse setup. Using the radiation hydrodynamics code RALEF-2D, we investigate source properties such as EUV energy yield, droplet motion and source size, as well as the energy, number, and direction of emitted ions. In the second half of the work, we study light absorption in a (non-LTE) plasma with a super-Gaussian electron velocity distribution, due to the Langdon effect. We derive a simple formula for the laser absorption, in which the Coulomb logarithm is modified by an additional term as a function of the super-Gaussian parameter. This has applications not just in nanolithography, but also in inertial confinement fusion.