ABSTRACT
Abstract. With the advent of tabletop X-ray lasers that operate at high repetition rate more emphasis is being put on finding useful applications for these lasers. The 14.7 nm Ni-like Pd X-ray laser at Lawrence Livermore National Laboratory is being used to do many interferometer experiments. As detailed quantitative comparisons are done between experiments and code simulations it is clear that some of the assumptions used to analyse the experiments need to be modified as one explores plasmas that are only a few times ionised. In the case of aluminium plasmas that have been analysed with interferometers there has been some unusual behaviour where the fringe lines bend the wrong way. In this work we will discuss how the index of refraction for aluminium is far more complicated than generally assumed because there are significant contributions to the index from the continuum and line structure of the bound electrons that can dominate the free electron contribution and even cause the index to be greater than one. We will also discuss some potential applications of the high repetition rate Ne-like Ar X-ray laser at 46.9 nm. In particular we will present modelling that shows how the Ar laser could be used to modify the absorption coefficient of a helium plasma and allow one to study the kinetics of plasmas with very low temperatures of a few eV. We will also discuss frequency doubling of the 46.9 nm laser.
