HEDgeHOB



High Energy Density Matter generated by Heavy Ion Beams

Mission

In the environment that we are used to, matter occurs predominantly in the solid, liquid or gaseous phase. However in the universe at large, the situation is quite different. Most of the matter in the universe exists as Dark Matter or as Dark Energy and we know very little about it yet. The small fraction of visible matter exists predominantly either as hot dense plasma in the interior of stars or in stellar atmospheres, or as hot plasma of very low density in interstellar space. Therefore plasma is viewed as the fourth state of matter, following the idea that as heat is added to a solid, it undergoes a phase transition to a liquid. If more heat is added the phase transition to a gas occurs. The addition of still more energy leads to a regime, where the thermal energy of the atoms or molecules forming the gas is so large, that the electrostatic forces which ordinarily bind the electrons to the atomic nucleus are overcome. The system then consists of a mixture of electrically charged particles like ions and electrons and neutral particles as well. In this situation, the long-range Coulomb force is the factor that determines the statistical properties of the sample. Plasmas occur naturally only as a transient phenomenon in lightning or in the aurora. The practical application of man made plasmas is very extensive and ranges from material modification, surface cleaning, and micro fabrication of electronic components to the future prospects of energy production in fusion plasmas.

 

Only very little is known about the bulk properties of matter in high energy density states. It is therefore an interesting field with promising applications to astrophysics, plasma physics and material sciences. As soon as we will be able to investigate high energy density samples under reproducible conditions in the laboratory with high repetition rate, we can expect a rapid progress in this field. Traditional methods to generate high energy density states are based on dynamic shock compression. Chemical explosions, high current Z-pinches, high power lasers and in a few cases even nuclear explosions were used to expose matter to high pressure up to the Gbar regime. As a consequence the investigated sample undergoes a number of phase transitions during the experiment.

 

Intense heavy ion beams open a new pathway to address this research experimentally. The unique energy deposition characteristics of heavy ion beams assure that macroscopic volumes are heated fast and in a very homogeneous way, such that temperature gradients as well as density gradients are very low compared to other methods.

 

Already today GSI accelerators deliver the most intense heavy ion beam for plasma physics experiments. The beam parameters of the new FAIR facility outnumber the current status in many respects: it is not only the absolute number of particles per bunch that will increase by about 3 orders of magnitude, but also the beam power will increase by a factor of 3000 due to pulse compression down to 50 ns (see Tab. 1). The specific energy deposition will increase from 1 kJ/g, which is a typical value for current experiments, to abot 600 kJ/g. This opens the possibility to reach out into currently inaccessible parameter regimes for high energy density (HED) states of matter, which is synonymously also called the regime of Warm Dense Matter (WDM).


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NEWS

21st International Symposium on Heavy Ion Inertial Fusion (HIF2016)

July 18th-22nd, 2016

Astana, Kazakhstan

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INTERNATIONAL EMMI Workshop on Plasma Physics at FAIR

July 11th -13th, 2016

FAIR/GSI Helmholtzzentrum Darmstadt

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