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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 114 (1992), S. 3983-3985 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1090-6487
    Keywords: 52.50.Jm ; 52.25.Jm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new approach for investigation of the generation of fast ions and hot electrons inside the same plasma volume in laser-produced plasmas is proposed. It is based on the spectroscopic observation of line radiation from singly and doubly excited levels with simultaneous high spectral and spatial resolution. The experimental results demonstrate the observation of fast ions from highly charged target material inside the plasma volume and suggest that the generally accepted scaling relations are seriously invalid under certain conditions. Even at rather modest intensities ions with energies of several MeV are observed.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 4379-4389 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The heavy ion synchrotron, SIS-18 (that has an 18 Tm magnetic rigidity), at the Gesellschaft für 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 simulations, the hydrodynamic and thermodynamic response of a solid lead cylindrical target that is irradiated with the future SIS-200 beam, which has a particle energy of 400 MeV/u. The beam focal spot is assumed to be circular and the power deposition profile is considered to be Gaussian along the radial direction. Calculations have also been done using a beam that has a ring-shaped (annular) focal spot that interacts with solid as well as hollow lead cylinders, respectively. In all the above cases it has been assumed that the cylinder length is shorter than the range of 400 MeV/u uranium ions in solid lead so that the Bragg peak does not lie inside the target and the energy deposition is almost uniform along the particle trajectory. These simulations show that it will be possible to create extended volumes of high-density, strongly coupled plasmas using the future SIS-200 beam. © 2000 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 611-615 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper, we show with the help of two-dimensional numerical simulations that the specific power deposition by a heavy ion beam in matter may significantly decrease due to hydrodynamic expansion of the target during irradiation. It has also been shown that in order to maximize the specific energy deposition, one is required to determine an optimum set of beam and target parameters including ion energy, beam radius, and pulse length. Three different values for the beam radius, namely, 0.5, 1.0, and 1.5 mm are considered, respectively. The target is a solid lead cylinder, which is irradiated by a uranium beam that consists of 1012 ions with a particle energy of 400 MeV/u. Such beam parameters will be available at the future heavy ion synchrotron, SIS-200 (with a magnetic rigidity of 200 Tm) at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt. It is also assumed that the beam is incident on one face of the cylinder and the cylinder length is less than the range of the projectile ions. The ions therefore penetrate the target, deposit a fraction of their energy in the target material along their trajectory, and escape through the opposite face of the cylinder with a substantially reduced energy. The Bragg peak therefore lies outside the target and the energy deposition is approximately uniform along the target length. This beam–target configuration generates an extended volume of high-energy–density matter, without any sharp gradients. © 2001 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 796-816 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper discusses the feasibility of employing heavy-ion cluster beams to generate thermal radiation that can be used to drive inertial fusion capsules. The low charge-to-mass ratio of a cluster may allow the driver beam to be focused to a very small spot size with a radius of the order of 100 μm, while the low energy per nucleon (of the order of 10 keV) may lead to a very short range of the driver particles in the converter material. This would result in high specific power deposition that may lead to a very high conversion efficiency. The problem of cluster stopping in cold matter, as well as in hot dense plasmas has been thoroughly investigated. The conversion efficiency of cluster ions using a low-density gold converter has also been calculated over a wide range of parameters including converter density, converter geometry, and specific power deposition. These calculations have been carried out using a one-dimensional hydrodynamic computer code that includes a multigroup radiation transport scheme [Ramis et al., Comput. Phys. Commun. 49, 475 (1988)]. The problem of symmetrization of this radiation field in a hohlraum with solid gold walls has also been thoroughly investigated using a three-dimensional view factor code. The characteristics of the radiation field obtained by this study are used as input to capsule implosion calculations that are done with a three-temperature radiation-hydrodynamic computer code MEDUSA-KAT [Tahir et al., J. Appl. Phys. 60, 898 (1986)]. A reactor-size capsule which contains 5 mg deuterium–tritium (DT) fuel is used in these calculations. The problem of using a fuel mixture with a substantially reduced tritium content has also been discussed. © 1997 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 4426-4455 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents one- and two-dimensional computer simulations of the hydrodynamic response of solid cylindrical targets made of different materials that are irradiated by intense beams of energetic ions. The beam parameters considered in this study correspond to the design parameters of the heavy ion beam that will be produced at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt heavy ion synchrotron facility (SIS) in 1999. A few calculations, however, were also done using the beam parameters that are currently available at the SIS. Different values for specific energy deposition including 1, 10, 50, and 100 kJ/g, respectively, have been considered, whereas a number of different pulse lengths, namely, 10, 50, 100, and 200 ns, have been assumed. Various target materials, for example, solid lead, solid neon, and solid hydrogen, have been used. It is expected that this simulation study will be very helpful in the design of efficient targets for the future experiments at the GSI. These experiments will hopefully provide very useful information about many important basic physics phenomena, such as enhanced energy loss of heavy ions in hot dense plasmas, equation-of state (EOS) of matter under extreme conditions, material opacity and shock wave propagation. Another very interesting experiment with important practical implications that could be done at this facility may be the creation of metallic hydrogen by imploding appropriately designed multilayered targets containing a layer of frozen hydrogen. This paper presents the design of such a target, together with implosion simulations of this target using a hydrodynamic simulation model. These simulations show that it may be possible to compress the frozen hydrogen to achieve the theoretically predicted physical conditions necessary for hydrogen metallization (a density of the order of 1 to 2 g/cm3, a temperature of a few 0.1 eV and a pressure of about 2–5 megabar). In some cases, compression of frozen deuterium was also studied. © 1998 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 3735-3746 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Heavy-ion clusters are considered for driving directly a pellet for inertial confinement fusion. They are shown to be effective at much lower energy than requested for heavy atomic ions. Multifragmentation, arising from a Coulomb explosion, in the target, is discussed with a maximum entropy hypothesis. Direct driving pressure imparted to a deuterium–tritium (DT) pellet is estimated through the ion debris range in the target. The correlated stopping of N ions flowing close to the initial projectile trajectory is seen to be much larger than the uncorrelated one. Specific attention is paid to a few regular geometrics of cluster ion debris stopped in a lithium pusher. The calculations elaborate on the very high driving pressure obtained, for the case of a solid-state density of cluster ion projectiles around the pellet (moving tamper). A target containing 4 mg of deuterium and tritium fuel is demonstrated to be thus imploded in 5 nsec. A driving pressure of 500 Mbars yields an energy output of 630 MJ. This result can be obtained with an initial cluster kinetic energy smaller than 20 keV/amu.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 3 (1991), S. 1717-1727 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents numerical simulations of compression, ignition, and burn of a radiation-driven inertial fusion capsule suitable for use in a heavy-ion-beam-driven laboratory microfusion facility to achieve breakeven (thermonuclear energy output=input radiation energy). These simulations have been carried out using a one-dimensional, three-temperature, Lagrangian computer code medusa-kat [J. Appl. Phys. 60, 898 (1986)]. The basic capsule design is simple and consists of a thin gold microballoon coated with a beryllium ablator. A high-pressure gaseous deuterium–tritium (DT) fuel is filled in the capsule. The capsule is driven by a shaped radiation pulse having a prepulse corresponding to a radiation temperature of 100 eV and a main pulse with a temperature of 300 eV. A parameter study of the capsule gain, G versus input radiation energy over a range 52–76 kJ, has been carried out. The fuel mass has also been varied over a range 0.3–0.8 μg. It has been found that G∼1 can be achieved with an absorbed radiation energy of 70 kJ provided that the fuel mass lies between 0.5 and 0.7 μg. These simulations have also been repeated over the same parameter range but using an unshaped pulse with a constant radiation temperature of 300 eV. An overall reduction of 10%–30% has been observed in the gain curves in this case.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 275-288 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Analytic and numerical solutions for the problem of the interaction of intense ion beams with matter in the form of plane targets are considered in this paper. The theory of the interaction of protons with matter at low energies is discussed and calculations are presented for the energy loss of protons in aluminum and gold. Zero- and one-dimensional models are developed and the results are compared to numerical simulations carried out with the one-dimensional Lagrangian hydrodynamic code medusa [Comp. Phys. Comm. 1, 271 (1974)], which has been extended to include the various physical effects needed to carry out realistic simulations of the interaction of ion beams with matter. The theory and simulation of the acceleration of foils by intense ion beams is also considered and representative results are given. The theoretical results are used to investigate the optimum conditions in which to carry out stopping power experiments for ions in hot, dense plasmas, so that the theory can be tested. These results are needed in order to perform more realistic pellet calculations for inertial fusion.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1526-1538 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper detailed simulations are presented of radiation-hydrodynamic response of gaseous cylindrical targets irradiated with heavy-ion beams that will be produced at the Gesellschaft für Schwerionenforschung, Darmstadt, using a heavy-ion synchrotron (SIS) [Heavy Ion Fusion, AIP Conference Proceedings No. 152 (AIP, New York, 1986), p. 23]. The purpose of this work is to explore material conditions for which the thermal radiation effects can be maximized. This is desirable in order to study a number of interesting and important effects including maximization of conversion efficiency of the ion beam energy to thermal radiation and measurement of the target opacity in the SIS experiments. It is expected that the SIS beams will produce a specific deposition power of 10 TW/g. The simulations in this paper show that a temperature of the order of 10 eV could be achieved by the SIS beams using homogeneous, cylindrical Xe targets. It has been shown that with the help of these computer simulations one should be able to measure the target opacity in these experiments within a factor of 3. Also these calculations show that in the SIS experiments one should be able to have a 50% conversion efficiency using a Xe target under optimum conditions. It has been found that the radiation effects will be optimized in the SIS experiments if the initial target density is of the order of 10−3 g/cm3. If the initial density is too high (of the order of 10−1 g/cm3 or more), hydrodynamic effects will dominate, while, on the other hand, if the initial density is too low (of the order of 10−4 g/cm3 or less), the electron thermal conductivity will take over.
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