A. Shutov

Numerical simulations of nonstationary fronts and interfaces by the Godunov method in moving grids

A Godunov scheme is proposed for the simulation of impact problems and detonations where nonstationary fronts and interfaces are tracked as boundaries of subregions that move in time. In each subre...

Target heating in high-energy-density matter experiments at the proposed GSI FAIR facility: Non-linear bunch rotation in SIS100 and optimization of spot size and pulse length

The Gesellschaft fur Schwerionenforschung ~GSI! Darmstadt has been approved to build a new powerful facility named FAIR ~Facility for Antiprotons and Ion Research! which involves the construction of a new synchrotron ring SIS100. In this paper, we will report on the results of a parameter study that has been carried out to estimate the minimum pulse lengths and the maximum peak powers achievable, using bunch rotation RF gymnastic-including nonlinearities of the RF gap voltage in SIS100, using a longitudinal dynamics particle in cell ~PIC! code, ESME. These calculations have shown that a pulse length of the order of 20 ns may be possible when no prebunching is performed while the pulse length gradually increases with the prebunching voltage. Three different cases, including 0.4 GeV0 u, 1G eV 0u, and 2.7 GeV0u are considered for the particle energy. The worst case is for the kinetic energy of 0.4 GeV0u which leads to a pulse length of about 100 ns for a prebunching voltage of 100 kV ~RF amplitude!. The peak power was found to have a maximum, however, at 0.5‐1.5kV prebunching voltage, depending on the mean kinetic energy of the ions. It is expected that the SIS100 will deliver a beam with an intensity of 1‐2 3 10 12 ions. Availability of such a powerful beam will make it possible to study the properties of high-energy-density ~HED! matter in a parameter range that is very difficult to access by other means. These studies involve irradiation of high density targets by the ion beam for which optimization of the target heating is the key problem. The temperature to which a target can be heated depends on the power that is deposited in the material by the projectile ions. The optimization of the power, however, depends on the interplay of various parameters including beam intensity, beam spot area, and duration of the ion bunch. The purpose of this paper is to determine a set of the above parameters that would lead to an optimized target heating by the future SIS100 beam.

Calculations of high-power production target and beamdump for the GSI future Super-FRS for a fast extraction scheme at the FAIR facility

A superconducting fragment separator (Super-FRS) is being designed for the production and separation of radioactive isotopes at the future FAIR (Facility for Antiprotons and Ion Research) facility at Darmstadt. This paper discusses various aspects and requirements for the high-power production target that will be used in the Super-FRS experiments. The production target must survive over an extended period of time as it will be used during the course of many experiments. The specific power deposited by the high intensity beam that will be generated at the future FAIR facility will be high enough to destroy the target in most of the cases as a result of a single shot from the new heavy ion synchrotrons SIS100/300. By using an appropriate beam intensity and focal spot parameters, the target would survive after being irradiated once. However, the heat should be dissipated efficiently before the same target area is irradiated again. We have considered a wheel shaped solid carbon target that rotates around its axis so that different areas of the target are irradiated successively. This allows for cooling of the beam heated region by thermal conduction before the same part of the target is irradiated a second time. Another attractive option is to use a liquid jet target at the Super-FRS. First calculations of a possible liquid lithium target are also presented in this paper. One of the advantages of using lithium as a target is that it will survive even if one uses a smaller focal spot, which has half the area of that used for a solid carbon target. This will significantly improve the isotope resolution.A similar problem associated with these experiments will be safe deposition of the beam energy in a beamdump after its interaction with the production target. We also present calculations to study the suitability of a proposed beamdump.

Prospects of high energy density physics research using the CERN super proton synchrotron (SPS)

The Super Proton Synchrotron (SPS) will serve as an injector to the Large Hadron Collider (LHC) at CERN as well as it is used to accelerate and extract proton beams for fixed target experiments. In either case, safety of operation is a very important issue that needs to be carefully addressed. This paper presents detailed numerical simulations of the thermodynamic and hydrodynamic response of solid targets made of copper and tungsten that experience impact of a full SPS beam comprized of 288 bunches of 450 GeV/c protons. These simulations have shown that the material will be seriously damaged if such an accident happens. An interesting outcome of this work is that the SPS can be used to carry out dedicated experiments to study High Energy Density (HED) states in matter.

Generation of plane shocks using intense heavy ion beams: Application to Richtmyer–Meshkov instability growth studies

A design of a novel experiment that allows the generation of a well defined, steady, and strong plane shock wave employing an intense uranium ion beam that is incident on a wedge shaped compound target is presented. This technique will open up the possibility of carrying out unique high energy density physics experiments using these shock waves. One such experiment is to study the growth of Richtmyer–Meshkov instability in fluids as well as in solids, both in the linear and nonlinear regimes, as shown by detailed numerical simulations presented in this paper. The ion beam parameters used in this study correspond to those that will be available at the Facility for Antiprotons and Ion Research (FAIR) at Darmstadt.

Creation of strongly coupled plasmas using intense beams of 400 MeV/u uranium ions to be generated at the Gesellschaft für Schwerionenforschung (GSI) Darmstadt SIS-200

The heavy ion synchrotron, SIS-18 (that has an 18 Tm magnetic rigidity), at the Gesellschaft fur Schwerionenforschung (GSI), Darmstadt is a unique facility worldwide that delivers intense beams of energetic heavy ions. The GSI has plans to extend its accelerator capabilities by building a new synchrotron (SIS-200) with a much higher magnetic rigidity of 200 Tm. According to the preliminary design considerations, the SIS-200 will generate a uranium beam that will consist of at least 1012 particles and that will be delivered in a 50 ns long pulse. This beam will be used to study various interesting problems, including fragmentation of the projectile ions while passing through solid matter and creation of high-density, strongly coupled plasmas. For the former type of studies, a particle energy of 1 GeV/u has been considered to be appropriate, while for the latter case, a lower value of 400 MeV/u has been found to be most suitable. In this paper we present, with the help of two-dimensional numerical simulatio...

Metallization of hydrogen using heavy ion imploded multi-layered cylindrical targets

This paper shows with the help of two-dimensional hydrodynamic simulations that it may be possible to achieve theoretically predicted physical conditions required for hydrogen metallization in heavy ion imploded multi-layered cylindrical targets. These include a density of about 1 g/cm 3 , a pressure of 2-5 Mbar and a temperature of a few 0.1eV in the compressed hydrogen sample. In this study an intense uranium beam consisting of 10 12 ions having a particle energy of 400 MeV/u is considered. The ions are delivered in a single bunch that has a length of 50 ns. These beam parameters are the design parameters for the future 200 Tm synchrotron facility, SIS-200, that will be constructed at the Gesellschaft fur Schwerionenforschung (GSI), Darmstadt.

Fundamental studies of intense heavy-ion beam interaction with solid targets

Intense (10/sup 11/ particles/1 /spl mu/s /spl sim/300 MeV/u) heavy ion beams are generated in the heavy-ion synchrotron (SIS) of the GSI-Darmstadt facility. Large volumes of strongly coupled plasmas are produced by heavy ion beam interaction with solid targets, with plasma densities close to the solid state, pressures of about 100 kbar, and temperatures of up to 1 eV, with relevance for equation of state (EOS) of matter, astrophysics, and low-entropy shock compression of solids. The plasmas created by ion beam interaction with metallic converters and cryogenic crystals were studied by backlighting shadowgraphy and by time-resolved spectroscopy in the visible and vacuum ultraviolet ranges. Low entropy weak shock waves induced by the ion beams in the metal-plexiglass multilayered targets were visualized by time resolved schlieren measurements, revealing induced multiple shockwaves with pressures higher than 15 kbar in a plexiglass window and propagation velocities up to 35% higher than the speed of sound in plexiglass at room temperature. To get an insight into the plasma dynamics, both types of experiments are simulated by the BIG-2 two-dimensional hydrodynamic code.

The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam–target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fur Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are considered to be the same as expected at the future SIS100 facility. The simulations show that due to multiple shock reflection between the cylinder axis and the lead–hydrogen boundary, one can achieve up to 20 times solid density in hydrogen while keeping the temperature as low as a few thousand K. The corresponding pressure is of the order of 10 Mbar. These values of the physical parameters lie within the range of theoretically predicted values for hydrogen metallization. We have also carried out a parameter study of this problem by varying the target and beam parameters over a wide range. It has been found that the results are very insensitive to such changes in the input parameters.

Simulations of full impact of the Large Hadron Collider beam with a solid graphite target

AbstractThe Large Hadron Collider (LHC) will operate with 7 TeV/c protons with a luminosity of 10 34 cm 22 s 21 . This requires twobeams, each with 2808 bunches. The nominal intensity per bunch is 1.15 10 11 protons and the total energystored in eachbeam is 362 MJ. In previous papers, the mechanisms causing equipment damage in case of a failure of the machineprotection system was discussed, assuming that the entire beam is deflected onto a copper target. Another failurescenario is the deflection of beam, or part of it, into carbon material. Carbon collimators and beam absorbers areinstalled in many locations around the LHC close to the beam, since carbon is the material that is most suitable toabsorb the beam energy without being damaged. In case of a failure, it is very likely that such absorbers are hit first,for example, when the beam is accidentally deflected. Some type of failures needs to be anticipated, such as accidentalfiring of injection and extraction kicker magnets leading to a wrong deflection of a few bunches. Protection of LHCequipment relies on the capture of wrongly deflected bunches with beam absorbers that are positioned close to thebeam. For maximum robustness, the absorbers jaws are made out of carbon materials. It has been demonstratedexperimentally and theoretically that carbon survives the impact of a few bunches expected for such failures. However,beam absorbers are not designed for major failures in the protection system, such as the beam dump kicker deflectingthe entire beam by a wrong angle. Since beam absorbers are closest to the beam, it is likely that they are hit first in anycase of accidental beam loss. In the present paper we present numerical simulations using carbon as target material inorder to estimate the damage caused to carbon absorbers in case of major beam impact.Keywords: Collimators and beam; Large Hadron Collider; Stoppers; Warm dense matter