N. A. Tahir

Present and future perspectives for high energy density physics with intense heavy ion and laser beams

Intense heavy ion beams from the Gesellschaft fur Schwerionenforschung ~GSI, Darmstadt, Germany! accelerator facilities, together with two high energy laser systems: petawatt high energy laser for ion experiments ~PHELIX! and nanosecond high energy laser for ion experiments ~NHELIX! are a unique combination to facilitate pioneering beam-plasma interaction experiments, to generate and probe high-energy-density ~HED! matter and to address basic physics issues associated with heavy ion driven inertial confinement fusion. In one class of experiments, the laser will be used to generate plasma and the ion beam will be used to study the energy loss of energetic ions in ionized matter, and to probe the physical state of the laser-generated plasma. In another class of experiments, the intense heavy ion beam will be employed to create a sample of HED matter and the laser beam, together with other diagnostic tools, will be used to explore the properties of these exotic states of matter. The existing heavy ion synchrotron facility, SIS18, deliver an intense uranium beam that deposit about 1 kJ0g specific energy in solid matter. Using this beam, experiments have recently been performed where solid lead foils had been heated and a brightness temperature on the order of 5000 K was measured, using a fast multi-channel pyrometer that has been developed jointly by GSI and IPCP Chernogolovka. It is expected that the future heavy ion facility, facility for antiprotons and ion research ~FAIR! will provide compressed beam pulses with an intensity that exceeds the current beam intensities by three orders of magnitude. This will open up the possibility to explore the thermophysical and transport properties of HED matter in a regime that is very difficult to access using the traditional methods of shock compression. Beam plasma interaction experiments using dense plasmas with a G-parameter between 0.5 and 1.5 have also been carried out. This dense Ar-plasma was generated by explosively driven shockwaves and showed enhanced energy loss for Xe and Ar ions in the energy range between 5.9 to 11.4 MeV.

Unique capabilities of an intense heavy ion beam as a tool for equation-of-state studies

Intense heavy ion beams open new possibilities in high-energy-density matter research. Due to the unique feature of the energy deposition process of heavy ions in dense matter (volume character of heating) it is possible to generate high entropy states in matter without the necessity of shock compression. Previously, such high entropy states could only be achieved by using the most powerful shock wave generators, like nuclear explosions or powerful lasers. In this paper this novel technique of heavy ion heating and expansion is proposed to explore new fascinating regions of the phase diagram, including the liquid phase, the evaporation region with the critical point, and strongly coupled plasmas.

High energy heavy ion jets emerging from laser plasma generated by long pulse laser beams from the NHELIX laser system at GSI

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 self focusing.

The Rayleigh-Taylor instability

A new approach to the Rayleigh-Taylor instability is presented that yields exact solutions for the simplest cases and provides approximate but still very accurate analytical expressions for important and more complex cases involving nonideal fluids. The approach is based on Newton’s second law and allows for an intuitive and physically appealing explanation of the mechanisms underlying the instability.

Symmetry analysis of cylindrical implosions driven by high-frequency rotating ion beams

A symmetry analysis of the cylindrical target implosion driven by a high-frequency rotating beam of heavy ions is presented. The non-uniformity generated by such a system is studied by developing an analytical model and by performing two-dimensional simulations. The results show that the asymmetry in the driving pressure depends on the number N of beam revolutions as N−n and the power index n is determined by the time variation of the power pulse. For a box pulse, it is n = 1 and for a parabolic pulse, it is n = 2. In the latter case symmetry of 1% can be achieved at the end of the pulse by using N = 10.

Ultrahigh compression of water using intense heavy ion beams: laboratory planetary physics

Intense heavy ion beams offer a unique tool for generating samples of high energy density matter with extreme conditions of density and pressure that are believed to exist in the interiors of giant planets. An international accelerator facility named FAIR (Facility for Antiprotons and Ion Research) is being constructed at Darmstadt, which will be completed around the year 2015. It is expected that this accelerator facility will deliver a bunched uranium beam with an intensity of 5x10(11) ions per spill with a bunch length of 50-100 ns. An experiment named LAPLAS (Laboratory Planetary Sciences) has been proposed to achieve a low-entropy compression of a sample material like hydrogen or water (which are believed to be abundant in giant planets) that is imploded in a multi-layered target by the ion beam. Detailed numerical simulations have shown that using parameters of the heavy ion beam that will be available at FAIR, one can generate physical conditions that have been predicted to exist in the interior of giant planets. In the present paper, we report simulations of compression of water that show that one can generate a plasma phase as well as a superionic phase of water in the LAPLAS experiments.

Compression of a cylindrical hydrogen sample driven by an intense co-axial heavy ion beam

The compression of a cryogenic hydrogen cylindrical sample contained in a hollow gold target driven by an intense co-axial uranium beam has been studied. The ion distribution is assumed to be Gaussian in space and parabolic in time. Thehydrodynamicsofthetargetisanalyzedbymeansofone-andtwo-dimensionalnumericalsimulations.Aparametric study is performed to achieve the maximum average hydrogen density and temperature as a function of the sample radius, total number of ions and spread of the spatial ion distribution.Awindow in the beam-target parameters for which hydrogen compression is higher than a factor of 10 and temperature is below 0.2 eV has been found by considering a single bunch that contains 2 10 11 uranium ions delivered in 100 ns. In this range of high densities and low

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.

Impact of 7-TeV∕c large hadron collider proton beam on a copper target

The large hadron collider (LHC) will allow for collision between two 7TeV∕c proton beams, each comprising 2808 bunches with 1.1×1011 protons per bunch, traveling in opposite direction. The bunch length is 0.5ns and two neighboring bunches are separated by 25ns so that the duration of the entire beam is about 89μs. The beam power profile in the transverse direction is a Gaussian with a standard deviation of 0.2mm. The energy stored in each beam is about 350MJ that is sufficient to melt 500kg of copper. In case of a failure in the machine protection systems, the entire beam could impact directly onto an accelerator equipment. A first estimate of the scale of damage resulting from such a failure has been assessed for a solid copper target hit by the beam by carrying out three-dimensional energy deposition calculations and two-dimensional numerical simulations of the hydrodynamic and thermodynamic response of the target. This work has shown that the penetration depth of the LHC protons will be between 10 and ...

Numerical analysis of a multilayered cylindrical target compression driven by a rotating intense heavy ion beam

Numerical analysis of the compression of a cylindrical cryogenic hydrogen sample surrounded by a high-density metallic shell driven by a heavy ion beam has been performed. The beam power profile is assumed to be parabolic in time and Gaussian in space and is made of uranium ions with a kinetic energy of 2.7 GeV0u. The beam center is positioned off axis and rotates around the target axis to provide a uniform annular energy deposition area. An acceptable symmetry in pressure is achieved if the number of revolutions is equal to or larger than 10. The maximum density and pressure of the hydrogen sample is studied as a function of the spread of the beam power Gaussian distribution and the rotation radius. This configuration leads to compressions of the order of 10 and a temperature of a few thousand Kelvin in hydrogen.