V. Gryaznov

Reflectivity of shock compressed xenon plasma

Experimental results [1] for the reflection coefficient of shock-compressed dense xenon plasmas at pressures of 1.6 – 17 GPa and temperatures around 30 000 K using a laser beam with λ = 1.06 μm are compared with calculations based on different theoretical approaches to the dynamical collision frequency. It is found that a reasonable description can be given assuming a spatial electron density profile corresponding to a finite width of the shock wave front of about 2 · 10–6 m.

Coulomb contribution to the direct current electrical conductivity of dense partially ionized plasmas

The Coulomb contribution to the electrical conductivity of partially ionized plasmas is discussed and its general behavior is investigated. Recent experiments on the direct current conductivity in shock wave induced argon and xenon plasmas are analyzed in this context. Within the relaxation time approach, the Coulomb contribution is extracted by eliminating the contribution of scattering from neutrals. Alternatively, the Coulomb contribution can be calculated directly within linear-response theory. In particular, from the latter approach a generalized Spitzer factor is derived for taking into account electron-electron interactions within the relaxation time approximation. Experimental results for the Coulomb contribution to the electrical conductivity are in reasonable agreement with an interpolation formula derived from linear-response theory.

Shockwave-driven, non-ideal plasmas for interaction experiments with heavy-ion beams

Plasma targets for measuring energy loss and charge-state distribution of heavy ions in non-ideal plasmas have been developed. Ar plasmas with Γ-parameters 0.55–1.5 could be realized and the interaction with several ion species studied. Here, the results for 5.9 MeV/u C ions are presented. The energy loss in plasma was reproduced in different experiments.

Generation of warm dense matter and strongly coupled plasmas using the High Radiation on Materials facility at the CERN Super Proton Synchrotron

A dedicated facility named High Radiation on Materials (HiRadMat) is being constructed at CERN to study the interaction of the 450 GeV protons generated by the Super Proton Synchrotron (SPS) with fixed solid targets of different materials. The main purpose of these future experiments is to study the generation and propagation of thermal shock waves in the target in order to assess the damage caused to the equipment, including collimators and absorbers, in case of an accident involving an uncontrolled release of the entire beam at a given point. Detailed numerical simulations of the beam-target interaction of several cases of interest have been carried out. In this paper we present simulations of the thermodynamic and the hydrodynamic response of a solid tungsten cylindrical target that is facially irradiated with the SPS beam with nominal parameters. These calculations have been carried out in two steps. First, the energy loss of the protons is calculated in the solid target using the FLUKA code [Fasso et...

Proposed studies of strongly coupled plasmas at the future FAIR and LHC facilities: the HEDgeHOB collaboration

Detailed theoretical studies have shown that intense heavy-ion beams that will be generated at the future Facility for Antiprotons and Ion Research (FAIR) (Henning 2004 Nucl. Instrum. Methods B 214 211) at Darmstadt will be a very efficient tool to create high-energy-density (HED) states in matter including strongly coupled plasmas. In this paper we show, with the help of two-dimensional numerical simulations, the interesting physical states that can be achieved considering different beam intensities using zinc as a test material. Another very interesting experiment that can be performed using the intense heavy-ion beam at FAIR will be generation of low-entropy compression of a test material such as hydrogen that is enclosed in a cylindrical shell of a high-Z material such as lead or gold. In such an experiment, one can study the problem of hydrogen metallization and the interiors of giant planets. Moreover, we discuss an interesting method to diagnose the HED matter that is at the centre of the Sun. We have also carried out simulations to study the damage caused by the full impact of the Large Hadron Collider (LHC) beam on a superconducting magnet. An interesting outcome of this study is that the LHC beam can induce HED states in matter.

Explosively Driven Dense Plasma Targets for the Ion Beam Experiments

Possibilities of the explosively driven technique to generate dense plasma targets for the ion beam experiments are discussed.

Pressure Ionization of Condensed Matter under Intense Shock Waves at Megabars

Physical properties of hot dense matter at megabar pressures are considered. The new experimental results on pressure ionization of hot matter generated by multiple shock compression of hydrogen and noble gases are presented. The low‐frequency electrical conductivity of shock compressed hydrogen, helium and xenon plasmas was measured in the megabar range of pressures. To reduce effects of irreversible heating and to implement a quasi‐isentropic regime strongly compressed matter was generated by the method of multiple shock compression in planar and cylindrical geometries. As a result, plasma states at pressures of the megabar range were realized, where the electron concentration could be as high ne ∼ 2×1023 cM −3, which may correspond to either a degenerate or a Boltzmann plasma characterized by a strong Coulomb and a strong inter‐atomic interaction. A sharp increase (by three to five orders of magnitude) in the electrical conductivity of a strongly nonideal plasma due to pressure ionization was recorded, and theoretical models were invoked to describe this increase. Opposite effect was observed for lithium compressed by multiple shock up to pressures ∼ 200 GPa, where electrical conductivity was sharply decreased as pressure increased.