Simulations of hydrodynamic flow in gas targets irradiated by intense ion beams

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Abstract
A two-dimensional hydrodynamic code is discussed. It includes the treatment of energy deposition by heavy ions and the calculation of transport coefficients. Loss terms due to volume radiation in the emission limit and a realistic equation of state (SESAME tables or the equation of state of an ionized gas including the solution of the Saha equations to determine the degree of ionization) are considered.Numerical simulations are performed to study the hydrodynamic flow in cylindrical tubes filled with the noble gases Argon and Xenon respectively. Target and beam parameters are chosen in close analogy to the GSI-RFQ beam-target experiments.The conditions for the formation of a shock wave at the interface between matter heated by the ion beam and cold matter are investigated. It turns out that, in addition to ionization effects, shock heating has a strong influence on the maximum target temperature. Depending on the temperatures to be reached with a given deposition power, either expansion or radiation cooling could be the dominant cooling mechanism. As a result we can conclude that hydrodynamic motion produces a lot of structure that should be observable in the GSI experiments.
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