Spectroscopy of XFEL heated Cu and x-ray absorption in laser-produced Warm Dense Cu a pár dalších témat

Warm Dense Matter (WDM) is a transitional state between solid and ideal plasmas. It can contain highly charged ions and moderate electron temperatures, while retaining rest of crystalline-like structure. In experimental conditions it can be typically created in a dynamical way by irradiation of solid targets with ultra-short pulse lasers. The x-ray spectroscopy of plasma is a great way of studying this transitional state of matter, by using either a broadband x-ray beam as a backlighter for absorption measurement, or self-emission to observe the radiation of various charge states of present ions.

In this talk I will present two different experiments studying warm dense Copper with their results and a minimum of underlying theory. In the first case, the matter is heated by direct irradiation by optical laser (Draco, Dresden), and probed variable delay later by a 'Laser wakefield accelerated' (LWFA) betatron beam. From the x-ray absorption techniques we can infer both the electron and ion temperatures, therefore observing the heating and melting of the material. In the second case, the matter is created ('pumped') and probed simultaneously by the same pulse of the X-ray Free Electron Laser (European XFEL, Hamburg). Moderately charged ions are created within the duration of the pulse (~30 fs) and their Kα emission is stimulated by the beam. The self-emission spectra in this well described environment serves as a road map of various atomic transitions and non-equilibrium atomic-physics effects of those ions.