Development of APPA experiments and diagnostics for FAIR phase-0

The investigation of extreme states of matter at Mbar pressures and a few eV temperatures ("warm dense matter” WDM) is one of the main goals of the plasma physics program at FAIR. To measure the temperature of the WDM generated by intense ion beam heating at APPA cave, a new multi-wavelength pyrometer was built. It is a very precise, flexible, and portable pyrometer, which enables temperature measurements with a high time resolution of nanoseconds and spatial resolution of hundred microns. This pyrometer was applied at HHT experimental area in GSI with intense uranium and lead ion beams for test measurements of the surface temperature of different metals, such as iron, tungsten, tantalum, and copper in the temperature range of 1-4kK. Future development of this device with new detectors is currently in progress.

Another goal of the project is the development of PRIOR instrument and preparation of the set-up for future experiments in the APPA cave. Time-resolved in situ observations of comparatively slow processes with millisecond time resolution and at the same time very high spatial resolution (several tens of μm) are one of the possible applications of this device. Experiments on the measurement of viscosities of liquids and melts at high pressures between 1 - 4000 bar and temperatures between 100 - 1900 K should answer fundamental questions about the viscosity of mineral melts and liquid-liquid phase transformations. The technical performance of PRIOR instrument was demonstrated via the experiments on the sulfur viscosity and density measurements at the pressures of 90 bar and temperatures of up to 750 K.