Sulfur exhibits an unusual dependence of viscosity on temperature. An experimental setup was developed to study the viscosity of sulfur at pressures up to 100 bar and temperatures up to 500°C. Proton radiography was used to visualize the movement of a tungsten carbide ball placed in liquid sulfur. The experiment was conducted using the PRIOR II proton microscope (GSI Helmholtz Centre for Heavy Ion Research, Darmstadt, Germany). In this experiment, the SIS-18 accelerator operating mode with slow beam extraction was used for proton radiography for the first time. The viscosity of liquid sulfur was measured at a pressure of 90 bar and temperatures ranging from 190 to 320°C. It has been shown that impurities, including hydrogen sulfide, which appears in the sulfur melt at high temperatures, have a significant effect on the viscosity of sulfur.

Sulfur is a substance with an abnormal dependence of viscosity on temperature. An experimental setup was created to study the viscosity of sulfur at pressures up to 100 bar and temperatures up to 500 °C. To visualize the process of falling of a tungsten carbide ball located in molten sulfur, the proton radiography method was used. The experiment was carried out on a PRIOR-II proton microscope (Institute for Heavy Ion Research, GSI, Darmstadt, Germany). In this experiment, the operating mode of the SIS-18 accelerator with slow beam extraction was used for the first time for proton radiography. The viscosity of the sulfur melt was measured at a pressure of 90 bar and temperatures of 190—320 °C. It has been shown that the viscosity of sulfur is greatly influenced by impurities, including hydrogen sulfide, which appears in the molten sulfur at high temperatures.

A technique for measuring the spatial heterogeneity of the light yield of a proton radiography scintillator has been developed. It is based on the recording of digital images formed during the passage of a proton beam through a scintillator and the approximation of the intensity distribution in the beam cross section by a two-dimensional Gaussian-like function. The results of the spatial calibration of the light yield of a lutetium silicate scintillator obtained using a magneto-optical proton microscope PUMA are presented. It is shown that accounting of the spatial heterogeneity of the scintillator makes it possible to describe the transverse beam intensity at each point of the proton radiographic image with a mean accuracy of about 0.7%. Experimental data on fluctuations in the position of the beam center, its size, and shape in the scintillator plane of PUMA microscope were obtained. The proposed technique eliminates optical artifacts in the radiographic image caused by operation of the optical recording system and artifacts caused by the electron-optical shutter, provided that the signal is proportional to the intensity of the beam. It also eliminates or strongly suppresses optical artifacts in radiographic images due to changes in the efficiency of a charge-coupled digital camera.

A method has been developed for calculating the proton beam transmission of static objects with a quasi-uniform areal density from a single proton radiography image under the condition of a Gaussian-like transverse beam profile. The calculated images of the transmission are intended to reconstruct the density of the investigated objects. A proton radiography of static targets was performed on an experimental setup with special magnetic optics PUMA with a proton energy of 800 MeV and an intensity of 1010 particles per image. It is shown that the application of the method makes it possible to reconstruct the proton beam transmission of the object under study with an average relative error of approximately 1–1.2

The article describes possible experiments with explosively driven non-ideal plasma at the proton microscope at the Facility for Antiprotons and Ion Research. It is proposed to employ linear explosive tubes for plasma generation and to measure an areal density in shock-compressed plasma of argon and xenon. The proposed experiments will provide valuable information on influence of strong interparticle interactions on thermodynamic properties of strongly coupled plasma. The density measurement will help the researchers to understand the nature of wall and wire precursors arising in the shock tubes.

A high explosive shock tube of non-ideal gaseous plasma for proton radiography is described. The gas dynamic flow in the shock compressed xenon at initial pressure of 7 bar was investigated in the tube. The velocity of the shock wave in xenon and the associated particle velocity were measured by a high-speed rotating mirror streak camera. Experimental time-distance data was used for approximation of the velocities by exponential decay functions. The shock tube is intended for generation of non-ideal plasma of xenon at the pressure of 5-12 kbar, the density of 0.24-0.3 g/cm(3) when the initial pressure is about 7 bar.

A radiographic setup for an investigation of fast dynamic processes with areal density of targets up to 5 g/cm is under development on the basis of high-current proton linear accelerator at the Institute for Nuclear Research (Troitsk, Russia). A virtual model of the proton microscope developed in a software toolkit Geant4 is presented in the article. Fullscale Monte-Carlo numerical simulation of static radiographic experiments at energy of a proton beam 247 MeV was performed. The results of simulation of proton radiography experiments with static model of shock-compressed xenon are presented. The results of visualization of copper and polymethyl methacrylate step wedges static targets also described.

Experiments on initiation of nitromethane sensitized by diethylenetriamine in weight proportion 98/2 by exploding wires were conducted. Several conditions of initiation of low speed detonation were determined.

A radiographic facility for an investigation of fast dynamic processes with areal density of targets up to 5 g/cm2 is under development on the basis of high-current proton linear accelerator at the Institute for Nuclear Research (Troitsk, Russia). A virtual model of the proton microscope developed in a software toolkit Geant4 is presented in the article. Fullscale Monte-Carlo numerical simulation of static radiographic experiments at energy of a proton beam 247 MeV was performed. The results of simulation of proton radiography experiments with static model of shock-compressed xenon are presented. The results of visualization of copper and polymethyl methacrylate step wedges static targets also described.

The article reviews the design and physical applications of high‐explosive generators for dense low‐temperature plasma. The PUMA proton microscope with magnetic optics at the Institute for Theoretical and Experimental Physics by A.I. Alikhanov of National Research Centre «Kurchatov Institute» (Moscow, Russia) was used to diagnose the plasma. The generators were developed for measurements of the equation of state of non‐ideal plasma, investigation of phase transitions in hydrogen or molecular gases, and studies of the properties of the interior of Giant planets. A proposal was made to repeat the experiments with explosive generators using the proton microscope PRIOR (Proton Microscope for Facility for Anti‐proton and Ion Research) at the GSI Helmholtzzentrum fur Schwerionenforschung (Darmstadt, Germany) and at the designed proton microscope at the Institute for Nuclear Research (Troitsk, Russia).

Early Experiments at FAIR in 2018 ‐ 2022 suggested by the HEDgeHOB collaboration in the field of non‐ideal plasma physics are discussed. Specific energies of 5‐10 kJ/g, pressures of 1‐2 GPa and temperatures of 1‐2 eV are expected to be reached in the substance at the first experiments with a U +28 beam with the energy of 0.2 AGeV and maximal intensity 3 · 10 10 per impulse. It will provide the possibility to investigate the two phase region including the critical point of several metals in HIHEX (Heavy Ion Heating and EXpansion) experiments with the plane and cylindrical geometry, realizing regimes of quasi‐isochoric heating, isentropic expansion and compression when the flow strikes the target. Analysis of thermal radiation transfer will give information on the vaporization dynamics. Measurements of electrical conductivity and optical properties on the supercritical adiabat will disclose information on the insulator to metal transition under these conditions. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A proton radiography facility with the use of magnetic optics (PUMA proton microscope) has been developed at the TWAC-ITEP accelerator-accumulator facility (the ITEP terawatt accumulator) for measuring the substance density distribution inside static and dynamic objects using the proton beam with an energy of 800 MeV. The proton radiographic image of an object of investigation placed in the object plane of the setup is formed in the plane of the detector with magnification K = 4 with the aid of the magneto-optical system consisting of four quadrupole lenses on permanent magnets. The PUMA facility is intended for measuring objects with an areal density of up to 20 g/cm 2 with a field of vision as large as 20 mm in diameter. The spatial resolution of radiographic images depends strongly on the areal density of the object of investigation. For the PUMA facility, the spatial resolution varies from 60 to 115 μm at an areal density of 0.46–17 g/cm 2 , respectively. The dynamical state of substance can be investigated in four consecutive radiographic images, since the time structure of the proton beam consists of four pulses, each with a duration of 47 ns (full width at half maximum (FWHM)) and an interval of 250 ns between them. This article is devoted to the description of the proton microscope construction. The main metrological characteristics of the facility are described using experiments with static and dynamic objects as an example.

The behaviour of Pb during isentropic compression on the front surface of a sapphire window (Fig. 1) was analyzed using a fast multi-channel pyrometer [1] and a specially developed imaging displacement interferometer (Fig. 2), designed to permit for the first time simultaneous temperature and pressure measurements (Fig. 3) by integrating the light collection optics for both systems on the pyrometer head. The specularly reflecting sapphire surface is imaged on a 50% beam-splitter through a doubly afocal system in order to keep the optical front flat. It is further relayed to the surface of the reference mirror which can be tilted remotely to allow for fringe tuning, and to an alignment camera and a streak camera, at a final resolution of ~50 μm. The imaging capability is used to solve fringe movement uncertainties.

In recent years studies of shock and detonation wave phenomena at extreme dynamic conditions were performed at proton radiography facility developed at the 800 MeV proton beam line of ITEP Terawatt Accelerator (ITEP-TWAC). The facility provides a multi-frame imaging capability at 50 μm spatial and 70 ns temporal resolution. The results of latest studies conducted there are presented, including explosion and detonation of pressed and emulsion high explosives, shock-induced dense non-ideal plasma of argon and xenon and shock loading of non-uniform metal surfaces. New compact explosive generators developed specifically for a use at proton radiography facilities are also presented.

Intense, focused heavy ion beams from SIS can deposit a high power and high energy in the target material. The primary excitation and subsequent relaxationand thermalization processes can be studies when gases are used as the target material. Light emission from the whole beam excited volume can be observed at least at wavelengths where the target material is optically thin. This aspect can be used to study the beam profile by optical methods.

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: