Spectral distribution of laser-driven hohlraum radiation

The plasma physics group at GSI investigates among other issues the energy loss of heavy ions in laser produced plasma [1]. The current experimental setup consists of an ion beam from the UNILAC accelerator that penetrates a thin carbon foil which is irradiated by an intense laser beam, e.g. the nhelix or PHELIX laser. The foil is turned into a hot plasma while the ions pass through it and the change in energy loss is measured by the time of flight. The laser cannot penetrate the foil and heats only the surface. This results in temperature as well as density gradients, complicating the analysis and theoretical description of the experiment. An advanced setup utilizes gold cavities which convert the monochromatic laser light into thermal black body radiation in the soft X-ray regime. A carbon foil is placed into a secondary cavity which is attached to the converter and will be heated by the X-rays volumetrically and homogeneously. As a preparation towards this setup the thermal radiation has to be characterized. The latest results are presented in this report.