Lithium fluoride single crystal window was used for optical light emission registration during quasi-isentropic compression of hydrogen to the pressures 100-150 GPa. Initially gaseous hydrogen samples at 78 K temperature and different pressures in the range 3-30 MPa were investigated. Recorded brightness temperature profiles in near infrared range of wavelength were analyzed to evaluate optical and transport properties of the investigated hydrogen sample and window. Two EOS models of hydrogen, with and without metallic region were used for 1-D simulation of it's properties under dynamic compression and estimation of hydrogen temperature within compressed layer. The obtained data demonstrate abrupt change of final temperatures after heating higher then 3500K.

The goal of this works is to study of the recombination process in the plasma of positive and negative ions produced in the afterglow of gas discharge. Experimental study of the recombination process in this system showed a strong suppression of the recombination rate compared to the classical model [1] for the ion plasma consisting of fluoride or fluorides of sulfur. In this case, there is increasing deviation of the recombination rate from the results predicted by the classical model with increasing nonideality parameter of the system. Explanation for these results is possible within the framework of approaches based on the use of molecular dynamics simulation, which allow a detailed description of the interaction between the ions and molecules produced plasma. This makes it possible to give an adequate description of the impact the formation of loose ion pairs to the recombination process in the plasma. An earlier study of the recombination process [2] showed that the increase of the plasma nonideality parameter should strongly suppress the recombination process. This is due to the formation of zones of manybody fluctuations between regions of the pair states and free electrons. In this case, the recombination rate should be described by the following formula:

A semiempirical multiphase equation of state for liquid hydrogen is given in view of the metal-dielectric transition. The position of the curve of “dielectric” fluid-conducting fluid equilibrium is determined. The experimental data of Nellis et al. [1] on abnormal compressibility of hydrogen are described within the constructed model. Predictions by the present model are compared with the experimental data of [1–4].

V. Ternovoi1, S. El Moussati 2, A. Fedenev 3, A. Fertman4, A.A. Golubev4, D.H.H. Hoffmann2, A. Hug2,3, B. Ionita2, A. Kantsyrev4, A. Khudomyasov 4, M. Kulish1, J. Ling2, N. Markov4, V. Mintsev1, D. Nikolaev1, A. Pyalling1, N. Shilkin1, V. Turtikov4, S. Udrea2, A. Ulrich5, D. Varentsov3, K. Weyrich3, D. Yuriev1, and Y. Zhao6 1IPCP, Chernogolovka, Russia; 2TUD, Darmstadt, Germany; 3GSI, Darmstadt, Germany; 4ITEP, Moscow, Russia; 5TUM, Munich, Germany;6IMP, Lanzhou, China

The results of experimental investigation of near - critical point states of liquid-vapour phase transition of of lithium, sodium and aluminium are presented. The metal foil samples were launched by explosively driven steel plate in Helium atmosphere; Li and Na - by direct impact and Al - by impact through the layer of helium. The heating of the Li and Na foils were performed by heat exchange with shocked He layer from the free side of sample; Al - by heating by multiple-shocked He from the back side of the foil. The temperature of sample surface was measured by fast multi-channel optical pyrometer. For Li and Na experiments the pressure was obtained from measured shock velocity in helium using base length technique; the 1-D simulation of the process of launching was performed to obtain pressure for Al experiments. The obtained experimental information allowed to evaluate liquid spinodal line, and the position of critical points on pressure - temperature plane for investigated metals.

Semi empirical equations of state for dielectric and plasma phases of liquid hydrogen were constructed. Dielectric phase was modeled as dissociating molecular - atomic mixture. This allowed to reproduce experimental results for single shock compressed hydrogen.Equilibrium line for plasma phase transition was built. For quasi isentropic compression according to the current model plasma phase transition occurs at the pressure 130 GPa.Model reproduces the experimental results for electrical conductivity of hydrogen under assumption that plasma phase clusters are formed in the dielectric phase of hydrogen.

The results of temperature and conductivity measurements of hydrogen, multiple shock compressed to the pressures 135 and 180 GPa are presented. Explosively driven steel plate with velocity up to 8 km/s was used for shock wave generation. Hydrogen with various initial pressures and temperatures was multiple shock compressed between steel bottom and sapphire window. Brightness temperature of hydrogen was measured by fast optical pyrometer. Electrical resistance of shocked hydrogen was measured simultaneously with optical pyrometer records. The conductivity of hydrogen decreased from 424 1/Om/cm at 2700 K down to 20 1/Om/cm at 6000 K along 135 GPa isobar. The conductivity of hydrogen decreased from 800 1/Om/cm at 5000 K down to 100 1/Om/cm at 6700 K along 180 GPa isobar. Experimental results are compared with various theoretical predictions.

D. Varentsov, S. El Moussati, A.D. Fertman, V.E. Fortov, A.A. Golubev, D.H.H. Hoffmann, A. Hug, M.I. Kulish, J. Ling, J. Menzel, V.B. Mintsev, N. Müller, D.N. Nikolaev, A. Pyalling, B.Yu. Sharkov, N.S. Shilkin, V.Ya. Ternovoi, V.I. Turtikov, S. Udrea, A. Ulrich, J. Wieser, and M. Zhukova GSI, Darmstadt, Germany; TUD, Darmstadt, Germany; IPCP, Chernogolovka, Russia; ITEP, Moscow, Russia; TUM, Munich, Germany; Coherent, Munich, Germany; TPU, Tomsk, Russia The primary goal of the ongoing warm dense matter (WDM) research by intense heavy ion beams at GSI is to develop essential diagnostic instruments and methods for future HEDgeHOB experiments at FAIR. This is being done in the frame of the experiment S331 fielded at the HHT area of GSI (see Fig. 1). t e m p e r a t u r e , o p a c i t y b a c k l i g h t i n g l a s e r i o n b e a m v e l o c i t y , p r e s s u r e b e a m $ t a r g e t a l i g n m e n t , b e a m d i a g n o s t i c s , s a m p l e e x p a n s i o n , s e l f $ e m i s s i o n e x p a n s i o n v e l o c i t y a n d s a m p l e v o l u m e p y r o m e t e r , r e fl e c t o m e t e r , s t r e a k 0 s p e c t r o m e t e r d i s p l a c e m e n t i n t e r f e r o m e t e r s a n d V I S A R s t r e a k < c a m e r a f o r s h a d o w g r a p h y a n d s c h l i e r e n f a s t i n t e n s i fi e d C C D c a m e r a

A. Hug1,2, S. El Moussati 2, A.D. Fertman4, V.E. Fortov3, A.A. Golubev4, D.H.H. Hoffmann2, M.I. Kulish3, J. Ling2, J. Menzel 2, V.B. Mintsev3, N. Müller2, D.N. Nikolaev3, A. Pyalling3, B.Yu. Sharkov4, N.S. Shilkin3, V.Ya. Ternovoi 3, V.I. Turtikov4, S. Udrea2, A. Ulrich5, D. Varentsov1, J. Wieser 6, and M. Zhukova7 1GSI, Darmstadt, Germany; 2TUD, Darmstadt, Germany; 3IPCP, Chernogolovka, Russia; 4ITEP, Moscow, Russia; 5TUM, Munich, Germany;6Coherent, Munich, Germany; 7TPU, Tomsk, Russia

Methods for creating near-critical states of the liquid-vapor phase transition during shock wave impact and optical methods for determining the positions of the boundaries of the two-phase region and the parameters of the critical point of the liquid-vapor phase transition (temperature, pressure) are described.

Magnetic properties of planar molecular magnets have been investigated by Mössbauer spectroscopy. A significant increase in the linewidth of the magnetic hyperfine structure with an increase in temperature is observed. A fluctuation model of magnetism for magnets lacking long-range magnetic order is proposed. This model describes the magnetic field distributions in these magnets in a wide temperature range with the use of a fixed set of coupling constants.

The modified equation of state of helium‐hydrogen mixtures was used for 1D hydrodynamic simulation of performed experiments the multiple shock compression of Jupiter and Saturn model atmospheres. That permitted us to obtain the isentropic compression at third and later steps of compression in pressure region 20 –150 GPa. It was shown, that the helium‐hydrogen mixtures become conductive due to appearance of hydrogen conductance. The intervals of pressure — temperature — density states of these transitions are 30–50 GPa − 4400–5000 K − 0.4–0.5 g/cm3 for Jupiter and 60–80 GPa − 4600–4800 K − 0.53–0.6 g/cm3 for Saturn in accordance with our new and previous experiments with pure hydrogen and gas mixtures.

In this work release isentropes of shocked porous molybdenum were investigated. Samples with an initial porosity m = ρ0/ρ = 1.4 and 3.1 were studied to achieve near-critical entropy states of metal after shock compression. Compressed samples were expanded into helium with different initial pressures. The brightness temperature of the metal and the helium shock wave velocity were measured with a fast multichannel pyrometer. The helium shock wave velocity was used to determine the final pressure (P S) of expansion of the metal and the velocity of metal expansion (W S). Location of peculiarities on the P S–W S and P S–T P curves of the isentropes gives the location of their entrance into the two-phase region. Estimation of the molybdenum critical temperature and pressure was carried out on the basis of the experimental data.

We discuss the different structural arrangements of NBu4[FeIICrIII(C2O4)3] layered compounds in their racemic and enantiomeric forms and related magnetic properties. For [MnIIFeIII(C2O4)3] networks of dimensionalities 2 and 3 Mössbauer spectroscopy was applied to study the FeIII sublattice magnetization. Unusual magnetic relaxation phenomena below TN were observed for both 2D and 3D networks.

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 n(e) similar to 2x10(23) 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 similar to200 GPa, where electrical conductivity was sharply decreased as pressure increased.

In this work release isentropes of shocked porous molybdenum were investigated. Samples with initial porosity m=rho(0)/rho=1.4; 3.1 were used to achieve near-critical entropy states of metal after shock compression. Shocked samples were expanding into helium with different initial pressures. The brightness temperature (T-P) of metal and the velocity of shock wave in helium were measured by fast optical pyrometer. Shock wave velocity value allowed to determine the final pressure (P-S) of expansion of metal and the velocity of metal expansion (Ws). Location of peculiarities on isentropes in P-S-W-S and P-S-T-P diagrams gives the location of their entrance into two-phase region. Estimation of molybdenum critical temperature and pressure were done on the basis of experimental data.

The intensity of optical radiation and resistance of a hydrogen-helium layer with He mass fraction Y = m He /( m He + m H )≅0.24, which corresponds to the composition of the outer layers of Jupiter’s atmosphere [2], were simultaneously measured under multiple shock compression up to 164 GPa in plane geometry. The initial pressure and temperature of the mixture were equal to 8 MPa and 77.4 K, respectively, and the velocity of steel strikers was equal to 6.2 km/s. These conditions allowed the generation of the final compressed curve close to the adiabatic states of Jupiter’s atmosphere according to the models proposed in [2, 3]. The conditions for the appearance of the conducting phase in the compression process and the achieved level of electrical conductivity were determined. The experimental data were compared with the one-dimensional fluid-dynamic simulation of the compression process using the equation of state for the mixture in a model similar to the one proposed in [3, 8]. The experimental data were also compared with the behavior of pure components having the same initial density as in the mixture and compressed to the same final pressure.