At the Helmholtz center GSI, PHELIX (Petawatt High Energy Laser for heavy Ion eXperiments) has been commissioned for operation in stand-alone mode and, in combination with ions accelerated up to an energy of 13 MeV/u by the heavy ion accelerator UNILAC. The combination of PHELIX with the heavy-ion beams available at GSI enables a large variety of unique experiments. Novel research opportunities are spanning from the study of ionmatter interaction, through challenging new experiments in

The energy deposition of ions in dense plasmas is a key process in inertial confinement fusion that determines the α-particle heating expected to trigger a burn wave in the hydrogen pellet and resulting in high thermonuclear gain. However, measurements of ion stopping in plasmas are scarce and mostly restricted to high ion velocities where theory agrees with the data. Here, we report experimental data at low projectile velocities near the Bragg peak, where the stopping force reaches its maximum. This parameter range features the largest theoretical uncertainties and conclusive data are missing until today. The precision of our measurements, combined with a reliable knowledge of the plasma parameters, allows to disprove several standard models for the stopping power for beam velocities typically encountered in inertial fusion. On the other hand, our data support theories that include a detailed treatment of strong ion-electron collisions.

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Recombination of Au 25+ ions with free electrons has been investigated in a mergedbeams experiment at the UNILAC of GSI in Darmstadt. Special emphasis was put on the recombination at very low energies in the electron-ion centre-of-mass frame. At E rel = 0 eV we found an enormous recombination rate exceeding the theoretical expectations for radiative recombination by a factor of 365. For further investigation of this enhancement, the electron density and the magnetic field guiding the electron beam were varied. While an increase of the electron density by a factor of 10 had little influence, the measured rate coefficient increased significantly with the magnetic field strength.

We present the first direct experimental test of the complex ion structure in liquid carbon at pressures around 100 GPa, using spectrally resolved x-ray scattering from shock-compressed graphite samples. Our results confirm the structure predicted by ab initio quantum simulations and demonstrate the importance of chemical bonds at extreme conditions similar to those found in the interiors of giant planets. The evidence presented here thus provides a firmer ground for modeling the evolution and current structure of carbon-bearing icy giants like Neptune, Uranus, and a number of extrasolar planets.

This Letter reports on the measurement of the energy loss and the projectile charge states of argon ions at an energy of 4  MeV/u penetrating a fully ionized carbon plasma. The plasma of n(e)≈10(20)  cm(-3) and T(e)≈180  eV is created by two laser beams at λ(Las)=532  nm incident from opposite sides on a thin carbon foil. The resulting plasma is spatially homogenous and allows us to record precise experimental data. The data show an increase of a factor of 2 in the stopping power which is in very good agreement with a specifically developed Monte Carlo code, that allows the calculation of the heavy ion beam's charge state distribution and its energy loss in the plasma.

PRL 116, 075001 (2016) PHYSICAL REVIEW LETTERS week ending 19 FEBRUARY 2016 0031-9007=16=116 (7)=075001 (5) 075001-1

The experimental data presented in this paper address the energy loss determination for argon at 4 MeV/u projectile energy in laser-generated carbon plasma covering a huge parameter range in density and temperature. Furthermore, a consistent theoretical description of the projectile charge state evolution via a Monte Carlo code is combined with an improved version of the CasP code that allows us to calculate the contributions to the stopping power of bound and free electrons for each projectile charge state. This approach gets rid of any effective charge description of the stopping power. Comparison of experimental data and theoretical results allows us to judge the influence of different plasma parameters.