Basko, M.

Bedacht, S.

Blazevic, A.

Cayzac, W.

Faik, S.

Frank, A.

Kraus, D.

Ortner, A.

Rienecker, T.

Roth, M.

Schaumann, G.

Schumacher, Dennis

Tauschwitz, An.

Wagner, F.

GSI Repository

Energy loss measurements of heavy ions in dense weakly coupled plasmagenerated by volumetric heating with hohlraum generated x-raysA. Ortner∗1, A. Blazevic2, M. Basko7, S. Bedacht1, W. Cayzac2, A. Frank5, S. Faik6, D. Kraus3, T.Rienecker6, G. Schaumann1, D. Schumacher2, An. Tauschwitz6,8, F. Wagner1, and M. Roth11Technical University Darmstadt, Germany ; 2GSI, Darmstadt, Germany; 3UC Berkeley, USA ; 6University Frankfurt,Germany ; 7KIAMMoscow, Russia ; 8HIC for FAIR, GermanyIn two experimental campaigns in 2012 precise mea-surements of the energy loss of Ca ions in dense, partlyionized carbon plasma have been carried out. An un-expected hight increase of the stopping power in thisweakly coupled plasma (Γ ≈ 0.5) has been measured.This was the first time, that ion stopping in such aplasma was measured.A 1 ns long, frequency doubled (λ = 527 nm) laser pulsewith a total energy of 150 J is converted in a sphericalcavity into X-rays with a radiation temperature of Tr ≈100 eV. This Plackian radiation heats up a secondary cylin-drical hohlraum to a radiation temperature of T r ≈ 30 eV.These soft X-rays are then used to heat volumetrically twothin carbon foils into a dense plasma state. A weakly cou-pled carbon plasma with an electron temperature of 5 eV to15 eV and electron density of up to 5 · 1021 cm−3 and anionization degree of 2+ to 4+ is generated. The propertiesof the primary as well as of the secondary hohlraum havebeen extensively studied by RALEF2D hydro-simulations[2, 3] and characterized in several experimental campaigns[4]. It has been shown, that no gold from the walls of thecylindrical hohlraum flows into the ion path for about 5 ns,which allows us to study the interaction of an ion beam ina pure carbon plasma.Fig. 1 shows the experimental setup used at the Z6 targetarea at GSI. The radiation temperature is measured with anX-ray streak spectrometer [4] and the electron density ofthe carbon plasma is characterized with a multi-frame in-terferometry. The ion energy loss is determined by a timeof flight measurement of the delayed ion bunches. Details∗ a.ortner@gsi.deion beamhigh energy laserToF distancestopdetectortargetinterferometryX ray streak cameraFigure 1: setup of the ion energy loss experimentcarbon plasmacold carbonempty hohlraumvacuum reference15 10 5 0 5 10050100150200time nsenergylossFigure 2: Energy loss results compared with an emptyhohlraum, cold carbon and vacuum measurements. t = 0ns indicates the beginning of the laser pulse. The gray areathe 5 ns time probing window.about the experimental setup and the double hohlraum tar-gets can be found in [5].The experimental results are shown in Fig. 2 and com-pared to measurements of the ion bunch delay in cold car-bon of the same areal density as well as to vacuum and to aempty hohlraum shot. The scale of the y-coordinate is nor-malized to the energy loss in cold carbon. As it can be seenon the ”empty hohlraum” - measurement, the gold plasmacoming from the wall, at earliest affects the ion bunches af-ter 5 ns. In plasma an increase of the energy loss of +70% is observed. Presently, our theoretical model basing onthe CaSP code for the stopping-power calculation and ona newly developed Monte-Carlo code for the charge-statedetermination, cannot explain such a strong increase [6].A crucial point to validate this theoretical approach is tocompare the calculated charge state distribution with ex-perimental data. For this reason, we will carry out a beamtime in september 2014 where we will focus on the mea-surement of the charge state distribution of the outcomingion beam after interacting with the plasma column.References[1] A. Ortner et al., GSI Report 2013-1, 374 p. (2013)[2] M. M. Basko et al., GSI Report 2011-03 (2011)[3] S. Faik et al., somewhere in this annual report[4] D. Schumacher, PhD-Thesis, TU Darmstadt, (2012)[5] A. Ortner et al., IFSA 2013 conference proceedings (2014)[6] A. Ortner et al., somewhere in this annual reportPNI-PP-05 GSI SCIENTIFIC REPORT 2013186 doi:10.15120/GR-2014-1-PNI-PP-05

Energy loss measurements of heavy ions in dense weakly coupled plasma generated by volumetric heating with hohlraum generated x-rays

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Energy loss measurements of heavy ions in dense weakly coupled plasma generated by volumetric heating with hohlraum generated x-rays

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