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The superconducting synchrotron SIS100 of the FAIR accelerator project will provide heavy ion beams of highest intensities. SIS100 is the first synchrotron with a special design, optimized for the control of ionization beam loss. Ionization beam loss is the most pronounced loss mechanism at operation with high-intensity, intermediate charge state heavy ions. The new synchrotron layout comprises an ion catcher system, which in combination with a charge separator lattice shall suppress dynamic vacuum effects.
A prototype cryogenic ion catcher, including a dedicated cryostat has been designed, manufactured, and tested under realistic conditions with beams from the heavy-ion synchrotron SIS18 at GSI. The gas desorption induced by the impact of heavy ions on this cryocatcher has been measured. For the very first time, a rise of desorption yield with increasing beam energy has been observed. However, measurements at room temperature have confirmed the known decrease of the pressure rise in the investigated energy regime. A transition temperature of 18 K, underneath hydrogen is adsorbed, could be verified several times. The results are significant and used to predict the ionization beam loss at operation of SIS100 at full-beam intensity.
The aim of the present work is the further development of the thermodynamics of hydrogen-like plasmas with densities on the order of 1027–1029 m−3 at temperatures of 106−108 K. Therefore, the Jacobi-Padé approximation for the so-called relative energy level shifts is applied to a quasineutral plasma consisting of six-fold and five-fold ionized carbon atoms and electrons. The relative energy level shift of the five-fold ionized carbon is determined by the difference between Coulomb and Debye potential, and by the kinetic energy of the particles. The shift caused by the kinetic energy (KES) has to be found considering the momentum space of the particles, so that nine-fold integrals in phase space have to be calculated. Quantum-physically, former numerical calculations of KES were only performed for particle states with zero angular quantum numbers. In the present work, a detailed, to a large extent analytical analysis of the KES is given for any angular quantum number, enabling also an improved analysis of future further-developed Jacobi-Padé formulae. Relative energy shifts of the bound-states of the fivefold ionized carbon are numerically obtained as function of the Mott parameter of the plasma. Dependencies of the shifts on main quantum numbers and orbital quantum numbers are discussed.
The high energy loss of heavy ions in matter as well as the small angular scattering makes heavy ion beams an excellent tool to produce almost cylindrical and homogeneously excited volumes in matter. This aspect can be used to pump short wavelength lasers. For the first time, a beam of heavy ions was used to pump a short wavelength gas laser in an experiment performed at the GSI ion accelerator facility in December 2005. In this experiment, the well-known KrF* excimer laser was pumped with an intense uranium beam. Pulses of an uranium beam compressed down to 110 ns (full width at half maximum) with initial particle energy of 250 MeV per nucleon were stopped inside a gas laser cell. A mixture of an excimer laser premix gas (95.5%Kr + 0.5%F2) and a buffer gas (Ar) in different proportions was used as the laser gas. The maximum beam intensity reached in the experiment was 2.5 × 109 particles per pulse, which resulted in 34 J/g specific energy deposited in the laser gas. The laser effect on the transition at λ = 248 nm has been successfully demonstrated by various independent methods. There, the laser threshold was reached with a beam intensity of 1.2 × 109 particles per pulse, and the energy of the laser pulse of about 2 mJ was measured for an ion beam intensity of 2 × 109 particles per pulse. As a next step, it is planned to reduce the laser wavelength down to the vacuum ultraviolet spectral region, and to proceed to the excimer lasers of the pure rare gases. The perspectives for such experiments are discussed and the detailed estimations for Xe and Kr cases are given. We believe that the use of heavy ion beams as a pumping source may lead to new pumping schemes on the higher lying level transitions and considerably shorter wavelengths, which rely on the high cross sections for multiple ionization of the target species.
The Large Hadron Collider (LHC) will operate with 7 TeV/c protons with a luminosity of 1034 cm−2 s−1. This requires two beams, each with 2808 bunches. The nominal intensity per bunch is 1.15 × 1011 protons and the total energy stored in each beam is 362 MJ. In previous papers, the mechanisms causing equipment damage in case of a failure of the machine protection system was discussed, assuming that the entire beam is deflected onto a copper target. Another failure scenario is the deflection of beam, or part of it, into carbon material. Carbon collimators and beam absorbers are installed in many locations around the LHC close to the beam, since carbon is the material that is most suitable to absorb 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 accidental firing of injection and extraction kicker magnets leading to a wrong deflection of a few bunches. Protection of LHC equipment relies on the capture of wrongly deflected bunches with beam absorbers that are positioned close to the beam. For maximum robustness, the absorbers jaws are made out of carbon materials. It has been demonstrated experimentally 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 deflecting the entire beam by a wrong angle. Since beam absorbers are closest to the beam, it is likely that they are hit first in any case of accidental beam loss. In the present paper we present numerical simulations using carbon as target material in order to estimate the damage caused to carbon absorbers in case of major beam impact.
This paper addresses the effect of target plasma electrons on the charge state of energetic ions, penetrating a target composed of bound as well as plasma electrons. Dynamic screening of the projectile Coulomb potential by the plasma electrons brings about a depression in the ionization energy of the ionic projectiles, as has been verified experimentally. This in turn makes the ionization cross-sections larger, while making the recombination cross-section smaller, thereby causing an increase in the ion charge state compared to the case of a gas target. The effect of the plasma environment, where the valence electrons are treated as plasma, is illustrated here for a 2 MeV carbon beam penetrating amorphous carbon targets of varying densities.
Cylindrical cryogenic targets are required to carry out the Laboratory Planetary Science scheme of the experiments of the High Energy Density matter Generated by Heavy Ion Beams collaboration at FAIR. In this paper, for the first time a thorough analysis of the problem of such targets' fabrication, delivery and positioning in the center of the experimental chamber has been made. Particular attention is paid to the issue of a specialized cryogenic system creation intended for rep-rate supply of the High Energy Density matter Generated by Heavy Ion Beams experiments with the cylindrical cryogenic targets.
This paper presents three–dimensional numerical simulations of thermodynamic and hydrodynamic response of a wheel shaped solid graphite production target for the super conducting fragment separator (Super–FRS) that is irradiated with a fast extracted high intensity uranium beam. These fragment separator experiments will be carried out at the future Facility for Antiprotons and Ion Research (FAIR), at Darmstadt. Previously, we reported simulation results that were carried out using two–dimensional computer codes which showed that one can use a solid graphite target for the Super-FRS for the highest intensity (5 × 1011 ions per spill) of the fast extracted uranium beam. Present results, however, have shown that due to three–dimensional effects the maximum intensity that can be used with such a target is 3 × 1011 ions per spill. A detailed comparison between two–dimensional and three–dimensional results is presented in this paper.
This paper describes a fast multi-channel radiation pyrometer that was developed for warm dense-matter experiments with intense heavy ion beams at the Gesellschaft für Schwerionenforschung mbH (GSI). The pyrometer is capable of measuring brightness temperatures from 2000 K to 50,000 K, at six wavelengths in the visible and near-infrared parts of the spectrum, with 5 ns temporal resolution, and several micrometers spatial resolution. The pyrometer's spectral discrimination technique is based on interference filters, which also act as mirrors to allow for simultaneous spectral discrimination of the same ray at multiple wavelengths.
Extensive numerical simulations have been carried out to design a viable solid graphite wheel shaped production target for the super conducting fragment separator experiments (Super-FRS) at the future Facility for Antiprotons and Ion Research (FAIR) using an intense uranium beam. In this study, generation, propagation and decay of deviatoric stress waves induced by the beam in the target, have been investigated. Maximum beam intensities that the target can tolerate using different focal spot sizes that are determined by requirements of good isotope resolution and transmission of the secondary beam through the fragment separator, have been calculated. It has been reported elsewhere that the tensile strength of graphite significantly increases with temperature. To take advantage of this effect, calculations have also been done in which the target is preheated to a higher temperature, that in practice can be achieved, for example, by irradiating the target with a defocused ion beam before the experiments are performed. We report results of a few examples using an initial temperature of 2000 K. This study has shown that employing such a configuration, one may use a solid graphite production target even for the maximum intensity of the uranium beam (5 × 1011 ion per bunch) at the Super-FRS.
Survival of the production target in successive experiments (with a repetition rate of 1 Hz) over an extended period of time is one of the key problems encountered in designing the Super-FRS (Superconducting Fragment Separator) at the future Facility forAntiprotons and Ion Research (FAIR). Because of the difficulties involved in construction of a liquid jet metal target, it is highly desirable to employ a solid production target at the Super-FRS. However, with the high beam intensities that will be available at the FAIR, the production target may be destroyed in a single experiment due to high specific energy deposition by the beam in the target material. The level of specific energy deposition can be reduced to an acceptable value by increasing the beam focal spot area. However, the spot size is limited by requirements of achieving good isotope resolution and sufficient transmission of the secondary beam through the system. The resolving power of the fragment separator is inversely proportional to the X-dimension of the focal spot whereas the transmission depends on Y-dimension only. It has been previously shown [Tahir et al., 2005c] that an elliptic focal spot with appropriate dimensions, will fulfill the above two conditions simultaneously and will also have a large enough area to reduce the specific energy deposition to an acceptable level for certain beam intensities of interest. In this paper we present numerical simulations of thermodynamic and hydrodynamic behavior of a solid graphite target that is irradiated by 1 GeV/u uranium beam in the intensity range of 1010 –1011 ions per bunch with a bunch length = 50 ns. These simulations have been carried out using a three-dimensional computer code, PIC3D, that includes elastic-plastic effects. This theoretical work has shown that up to a beam intensity of 1011 ions/bunch, one can employ a solid target while for higher intensities the target will be destroyed due to thermal stresses induced by the beam. It has also been found that a circular focal spot leads to minimum thermal stresses as it generates minimum pressure gradients compared to an elliptic focal spot, for the same specific energy deposition. Moreover, the stress level increases with an increase in the ellipticity of the focal spot. It is therefore recommended that one should use a circular focal spot for lower intensities provided that the criteria for isotope resolution and transmission are fulfilled.
This paper presents numerical simulations of thermodynamic and hydrodynamic response for solid targets that are irradiated with strongly bunched, highly focused, intense beams of energetic uranium ions. The main purpose of this work is to study the behavior of thermal stress waves induced in such targets by the incident ion beam. These theoretical studies will complement the experimental investigations that will be carried out in the near future at the Gesellschaft für Schwerionenforschung (GSI) plasma physics experimental area. These experiments will be performed using the existing heavy ion synchrotron, SIS18, which delivers 4 × 109 uranium ions in a single bunch with a length of about 125 ns. Other time structures, for example, a pulse that consists of a series of bunches, are also possible. The particle energy is on the order of 400 MeV/u and the beam can be focused to sub millimeter radius. This information concerning material response under intense beam loading will have important implications on designing a viable production target for the superconducting fragment separator, Super-FRS, which is going to be constructed at the future facility for antiproton and ion research (FAIR), Darmstadt, Germany, for the production and separation of exotic nuclei.
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.
The dependence of calcium ion subshell populations on the target density during the ion stopping process was analyzed using a five charge-state collisional-radiative model. The model, which consists of the ground and three excited states for every ion charge, was successfully compared with the experiment. The gas-solid difference of calcium ion charge state distribution has been numerically demonstrated. For Ca projectiles with energies of 4–11 MeV/u, the increase of the mean ion charge in solid target is explained by the increase of the total ionization rate and by suppression of the bound electron capture process at high densities of the stopping medium.
Scattering of energetic electron and proton beams by cold matter is significantly different from the scattering of these particles by plasma, which may be either highly ionized or dense strongly coupled plasma. This is due to the difference in the shielding of the target nuclei between the two cases. Quantitatively, we treat the problem by means of the Bethe Moliere multiple scattering theory and the version of this theory for plasma as derived by Lampe. We propose to use this effect as a plasma diagnostic tool, utilizing monoenergetic, well-collimated electron or proton beams produced either by femtosecond laser plasma interactions or by accelerators. The effect is first illustrated for simplicity, by calculating the widths of the angular distribution of scattered particles interacting with the extreme cases of very hot fully ionized carbon, and iron plasmas, and comparing these results to the corresponding cold material. The more relevant case of electron scattering from partially ionized iron and carbon plasmas covering the entire range from a cold to a completely ionized target is also dealt with here. This paper brings up and highlights the difference between scattering by plasma and by cold material in light of the recent proposals to employ particle beams for various fusion applications.
The new international facility for antiproton and ion research (FAIR), at Darmstadt, Germany, will accelerate beams of all stable isotopes from protons up to uranium with unprecedented intensities (of the order of 1012 ions per spill). Planned future experiments include production of exotic nuclei by fragmentation/fission of projectile ions of different species with energies up to 1.5 GeV/u at the proposed super conducting fragment separator, Super-FRS. In such experiments, the production target must survive multiple irradiations over an extended period of time, which in case of such beam intensities is highly questionable. Previous work showed that with full intensity of the uranium beam, a solid graphite target will be destroyed after being irradiated once, unless the beam focal spot is made very large that will result in extremely poor transmission and resolution of the secondary isotopes. An alternative to a solid target could be a windowless liquid jet target. We have carried out three-dimensional numerical simulations to study the problem of target heating and propagation of pressure in a liquid Li target. These first calculations have shown that a liquid lithium target may survive the full uranium beam intensity for a reasonable size focal spot.
The transport of high-current heavy-ion beams in plasma channels is a
promising option for the final transport in a heavy-ion fusion reactor,
since it simplifies the construction of the reactor chamber significantly.
Our experiments at the Gesellschaft für Schwerionenforschung
demonstrate the creation of 1 m long stable plasma channels and the
transport of heavy-ion beams. The article outlines the experimental setup
used at GSI and reports the results of beam transport measurements using
these long channels. The experiments demonstrate good beam transport
properties of the channel, indicating that channel transport is a viable
alternative to neutralized-ballistic transport.
High energy heavy ions were generated in laser produced plasma at
moderate laser energy, with a large focal spot size of 0.5 mm diameter.
The laser beam was provided by the 10 GW GSI-NHELIX laser systems, and the
ions were observed spectroscopically in status nascendi with high spatial
and spectral resolution. Due to the focal geometry, plasma jet was formed,
containing high energy heavy ions. The velocity distribution was measured
via an observation of Doppler shifted characteristic transition lines. The
observed energy of up to 3 MeV of F-ions deviates by an order of magnitude
from the well-known Gitomer (Gitomer et al.,
1986) scaling, and agrees with the higher energies of relativistic
Below is the complete Reference citation for Hoffmann et al.
Hoffmann, D.H.H., Blazevic, A., Ni, P., Rosmej, O., Roth, M.,
Tahir, N., Tauschwitz, A., Udrea, S., Varentsov, D., Weyrich, K. &
Maron, Y. (2005). Present and future perspectives for high energy
density physics with intense heavy ion and laser beams. Laser Part.
Below is the complete Reference citation for Neumayer et al.
Neumayer, P., Bock, R., Borneis, S., Brambrink, E., Brand, H.,
Caird, J., Campbell, E.M., Gaul, E., Goette, S., Haefner, C., Hahn, T.,
Heuck, H.M., Hoffmann, D.H.H., Javorkova, D., Kluge, H.-J., Kuehl, Th.,
Kunzer, S., Merz, T., Onkels, E., Perry, M.D., Reemts, D., Roth, M.,
Samek, S., Schaumann, G., Schrader, F., Seelig, W., Tauschwitz, A., Thiel,
R., Ursescu, D., Wiewior, P., Wittrock, U. & Zielbauer, B.
(2005). Status of PHELIX laser and first experiments. Laser Part.
This paper reports on the status of the PHELIX petawatt laser which is
built at the Gesellschaft fuer Schwerionenforschung (GSI) in close
collaboration with the Lawrence Livermore National Laboratory (LLNL), and
the Commissariat à l'Energie Atomique (CEA) in France. First
experiments carried out with the chirped pulse amplification (CPA)
front-end will also be briefly reviewed.