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.

A new high energy proton radiography facility PRIOR-II (Proton Microscope for FAIR) has been designed, constructed, and successfully commissioned at the GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany) pushing the technical boundaries of charged particle radiography with normal conducting magnets to the limits. The setup is foreseen to become a new and powerful user facility for carrying out fundamental science experiments in the fields of plasma and shock wave physics, material science, and medical physics. It will help address several unsolved scientific challenges, which require high-speed and precise non-invasive diagnostic methods capable of probing matter with up to 100 g/cm2 areal density. PRIOR-II is specifically designed to utilize the full timing capabilities of the SIS-18 synchrotron at GSI for ultra-fast dynamic experiments with up to 4 GeV protons and will also be fielded at the future FAIR facility, where higher proton energies and beam intensities will be available. This will enable experiment geometries with even higher areal densities, more flexible experiment timing, and further enhanced spatial resolution.

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.

Information about charged particles emitted by plasma of high-current discharges is of interest both from the point of view of understanding the fundamental processes occurring in pulsed plasma and for applied problems. Compact magnetic spectrometers based on permanent magnets make it possible to measure the flux of charged particles from a plasma under conditions of strong electromagnetic noise. Imaging plates (IP) are one of the most commonly used types of detectors for detecting charged particles in laser-plasma and electric-discharge experiments. This paper presents the results of calibration of the BAS-MS IP when detecting electrons and the BAS-TR IP when detecting helium and tungsten ions. Calibration dependences of the sensitivity of the BAS-MS IP for electrons in the energy range of 0.65–50 MeV and the sensitivity of the BAS-TR IP for tungsten ions in the energy range from 20 eV to 650 keV are obtained, taking into account the angles of incidence of particles on the detector.

The interaction of a heavy-ion beam with matter is a fundamental problem of plasma physics and high-energy density in matter physics. The paper presents the results of experimental studies of energy losses of Fe+2 ions with an energy of 100 keV/u in a hydrogen plasma. The experimental data of plasma free electron stopping power are compared with theoretical models.

We report on a precision energy loss measurement and theoretical investigation of 100  keV/u helium ions in a hydrogen-discharge plasma. Collision processes of helium ions with protons, free electrons, and hydrogen atoms are ideally suited for benchmarking plasma stopping-power models. Energy loss results of our experiments are significantly higher than the predictions of traditional effective charge models. We obtained good agreement with our data by solving rate equations, where in addition to the ground state, also excited electronic configurations were considered for the projectile ions. Hence, we demonstrate that excited projectile states, resulting from collisions, leading to capture-, ionization-, and radiative-decay processes, play an important role in the stopping process in plasma.

Currently, work is underway to create laser accelerators with beam focusing by plasma lenses. For effective focusing, it is necessary to investigate at which initiation of breakdown a discharge forms with a more uniform distribution of current density. Our studies have shown that the plasma distribution is uniform over a longer period of time, including the region of maximum current, if the discharge is initiated by an electron beam.

We study the gas discharge process under conditions when a relativistic electron beam is injected into the discharge tube after applying a high-voltage pulse. As a result, a plasma channel is created, a breakdown occurs, and a discharge develops. Comparative experiments were performed at different gas pressures under discharge conditions with and without electron beam initiation. They showed significant differences, especially during pinching and further development of the discharge.

The transfer of ions to a higher charge state is of central importance for the development of new accelerator facilities. That is why the comparative analysis of the current stripping alternatives is a relevant topic. Currently, mainly gas and foil strippers are used for increasing the particle charge state. Even when their efficiency or lifetime has proved to be less than optimal, as these alternatives either require great effort or are not suitable. Compared to the gas and foil stripper the alternative of using a plasma stripper has a much higher effectiveness and a higher lifetime [1-13] That is why the plasma stripper has been proposed for the FAIR project (Facility for Antiproton and Ion Research) in Darmstadt, Germany. To further develop this subject, the plasma physics group of the Institute of Applied Physics at the University of Frankfurt is researching on an alternative for the Z-pinch plasma cell. During our research, various prototypes and solutions have been investigated [4-6], [8], [11], [14-16]. As a result, the optimal ignition criterion for the inductively coupled plasma ignition was determined, the optimal geometry of the discharge vessel, the required particle density and temperature of the plasma were calculated. Different coil configurations have been developed, built and tested. With some of them (spherical theta pinch and spherical screw pinch), beam time experiments were performed. This contribution presents the current state of plasma strippers with fully ionized hydrogen with simultaneously high particle densities in the range of some 10(16) cm(-3) for FAIR. Charge distributions after the ion beam plasma and ion beam cold gas interactions were measured and compared. As expected, the effective state of charge after interaction with plasma was higher than after interaction with gas (q(p) = 32.84 versus q(gas) = 29.41).

The energy deposition and the atomic processes, such as the electron-capture, ionization, excitation and radiative-decays for slow heavy ions in plasma remains an unsolved fundamental problem. Here we investigate, both experimentally and theoretically, the stopping of 100 keV=u helium ions in a well-defined hydrogen plasma. Our precise measurements show a much higher energy loss than the predictions of the semi-classical approaches with the commonly used effective charge. By solving the Time Dependent Rate Equation (TDRE) with all the main projectile states and for all relevant atomic processes, our calculations are in remarkable agreement with the experimental data. We also demonstrated that, acting as a bridge for electron-capture and ionization, the projectile excited states and their radiative decays can remarkably influence the equilibrium charge states and consequently lead to a substantial increasing of the stopping of ions in plasma.

Regarding the development of new accelerator facilities for high-intensity ion beams, the transfer of ions to higher charged states is a prerequisite achieve the desired energies. At present, mainly gas and film stripper are used for increasing the particle charge state. However, the stripping technologies such as film and gas stripper either requires great effort or are not suitable. One promising alternative to the before mentioned methods is the use of a plasma as stripper. The advantages of a plasma stripper are a higher effectiveness as a gas stripper and a higher lifetime as a film stripper. For this reason, stripper is proposed for the FAIR project (Facility for Antiproton and Ion Research), a new international accelerator laboratory at the GSI in Darmstadt, Germany. In experiments with a Z-pinch plasma, the effect of a plasma as a stripper method for increasing the equilibrium charge states has already been demonstrated [1]. A disadvantage of Z-pinch, however, is the electrode erosion, whereby the lifetime of the system is limited. In the case of an inductive ignition of a plasma no electrode erosion occurs, and the magnetic field extends predominantly in the centre of the coil parallel to the beam has no influence on the beam optics. Due to a high interest in the stripping method based on the ion beam-plasma interaction, the plasma physics group of the Institute of Applied Physics at the University of Frankfurt is researching on an alternative for the Z-pinch plasma cell. During our research, various prototypes and solutions have been investigated. As a result, the optimal ignition criterion for the inductively coupled plasma ignition was determined, the optimal geometry of the discharge vessel, the required particle density and temperature of the plasma were calculated [2] [3]. Different coil configurations have been developed, built and tested [4] [5] [6]. With some of them (spherical theta pinch and spherical screw pinch), beam time experiments were performed [7]. This contribution presents the current state of plasma strippers with fully ionized hydrogen with simultaneously high particle densities in the range of some 1017 cm-3 for FAIR.

The HIPr-1 (Heavy-Ion Prototype) beam transport channel was designed for performing experiments to measure the energy losses in plasma, which was developed considering the results of the beam dynamics simulation.

На основании моделирования динамики пучка разработана конструкция канала транспортировки ускорителя ТИПр-1 (ТяжелоИонный Прототип) для исследования процессов торможения тяжелых ионов с энергией до 100 кэВ/а.е.м. в газоразрядной плазменной мишени.

This paper reports the measurement of the energy loss of protons at the energy of 100 keV penetrating a partially ionized hydrogen plasma. The plasma of ne ≈ 1015–16 cm−3; Te ≈ 1–2 eV and lifetime of about 8 µs is created by the hydrogen gas discharge. The experimental results show an increase of a factor of 2.8 in the energy loss, which are in good agreement with the Bethe, Standard Stopping Model, Li–Petrasso and Vlasov models’ predictions within the error limit. The Bethe–Bloch Coulomb logarithm term is found to increase by a factor of 4.0 for free electrons as compared with the situation where bound electrons prevail. The potential application of protons energy loss for diagnosing the electron density in plasma is proposed too.

A novel method to determine the total hydrogen density and, accordingly, a precise plasma temperature in a lowly ionized hydrogen plasma is described. The key to the method is to analyze the energy loss of swift heavy ions interacting with the respective bound and free electrons of the plasma. A slowly developing and lowly ionized hydrogen theta-pinch plasma is prepared. A Boltzmann plot of the hydrogen Balmer series and the Stark broadening of the H_{β} line preliminarily defines the plasma with a free electron density of (1.9±0.1)×10^{16}  cm^{-3} and a free electron temperature of 0.8-1.3 eV. The temperature uncertainty results in a wide hydrogen density, ranging from 2.3×10^{16} to 7.8×10^{18}  cm^{-3}. A 108 MHz pulsed beam of ^{48}Ca^{10+} with a velocity of 3.652  MeV/u is used as a probe to measure the total energy loss of the beam ions. Subtracting the calculated energy loss due to free electrons, the energy loss due to bound electrons is obtained, which linearly depends on the bound electron density. The total hydrogen density is thus determined as (1.9±0.7)×10^{17}  cm^{-3}, and the free electron temperature can be precisely derived as 1.01±0.04  eV. This method should prove useful in many studies, e.g., inertial confinement fusion or warm dense matter.