Basko, M.

Helfrich, J.

Kindler, B.

Lommel, B.

Roth, M.

Schaumann, G.

Tauschwitz, An.

GSI Repository

Target development for Warm Dense Matter researchJ. Helfrich∗1, G. Schaumann1, An. Tauschwitz2, M. Basko3, B. Lommel4, B. Kindler4, and M. Roth11TU Darmstadt, Germany; 2Uni Frankfurt, Germany; 3KIAM, Moscow, Russia; 4GSI, Darmstadt, GermanyIntroductionCarbon is one of the most abundant elements on earth.It’s behavior in the Warm Dense Matter regime at very highpressures in the Mbar area and several thousand degreesCelsius is part of current research. A better understand-ing of carbon under these conditions is important for theunderstanding of planetary cores, beam dumps for acceler-ators or as a component of plastic in inertial confinementfusion targets and for Equation of State systems to improveand benchmark this equation [1]. These exotic states can beachieved in the laboratory by a shock wave which is drivenby a laser. The final state depends on the laser intensity andthe initial carbon structure and density. In previous experi-ments it was possible to generate liquid carbon and to proveit with X-ray scattering. This was made possible by themethod of X-ray Thomson scattering, which is planned asa key diagnostic for the plasma physics research program atFAIR [2]. In the next step, the solid-liquid phase transitionregion should be determined more accurately. This will beintend with a new target geometry and a VISAR (VelocityInterferometer System for Any Reflector) detector.Target design and SimulationsA novel idea is to reduce the laser intensity for the shockgeneration so far that there is no phase transition to the liq-uid state and then initiate the solid liquid phase transitionusing a further shock. This should be achieved by the re-flection of a part of the initial shock wave from a fixed wallby a conical geometry (see figure 1).Figure 1: sketch of the cone targetThe shock wave is reflected on both sides and convergesat the center. Figure 2 shows a RALEF2D simulation of thetarget geometry [3]. In simulations it is clearly seen how∗ j.helfrich@gsi.dethe shock-wave is reflected from the gold wall resulting inan increase of the density and temperature of the shockedcarbon.gold wallreflected waveFigure 2: density increased by the reflected shock wavesimulated with the RALEF2D codeThe best reflective material has a high sound velocity anda high density such as osmium or uranium, but the process-ing, handling and safety aspects of these materials are notacceptable. The best compromise for the reflective wall isgold.Target productionTarget production is challenging due to the sub millime-ter size of the samples. Cones were made from a carbonrod which was processed with a CNC precision lathe at thetarget laboratory of the TU Darmstadt. In the next step, thecarbon was coated with gold. The gold coating was doneby DC sputtering under argon in the target laboratory ofGSI. For the shock wave reflection a good connection be-tween the gold and carbon is require which is ensured bythis method. This work was supported by BMBF project05P12RDFA1.References[1] S. H. Glenzer, R. Redmer, Rev. Mod. Phys. 81, 1625 (2009)[2] FAIR Baseline Technical Report (2006)[3] M. M. Basko, J. Maruhn and An. Tauschwitz, GSI ScientificReport 2009: GSI Report 2010-1, p. 410.GSI SCIENTIFIC REPORT 2013 PNI-PP-14doi:10.15120/GR-2014-1-PNI-PP-14 195

Target development for Warm Dense Matter research

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Target development for Warm Dense Matter research

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