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Beam-induced fluorescence of dense gas targets has been studied for its application to measure the transverse intensity distribution of energetic focused heavy ion beams. Mechanisms of light emission are discussed on the basis of measured wavelength- and time-resolved light emission of argon. Gas pressures from 10 mbar up to 1 bar have been used. Transverse beam intensity profiles of 200 – 400 AMeV 238U pulses from the heavy ion synchrotron SIS-18 at the Gesellschaft fur Schwerionenforschung, Darmstadt, Germany with up to 5 · 109 particles per pulse focused to a sub-millimeter spot have been recorded with argon and helium as target gases. Beam profiles recorded at the ArII lines by an optical filter resulted in the narrowest, most realistic beam diameters. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The problem of the nature of thermodynamic properties and the high level electrical conductivity of substances at high pressures and temperatures is one of the most key issues of physics of high energy densities. So called pressure ionization is one of the most impressive demonstrations of the strong coupling effects in plasma under compression. Noble gases are the simplest object of studying of these phenomena because of absence of molecules and spherical symmetry of their atoms. In the present paper we are trying to have a common look from the chemical plasma picture on the whole available massive of the experimental data on Ar and Xe in a wide range of the parameters: from gaseous densities of 0,01 g/cc and pressures of several kilobars up to extremely high densities corresponding to the insulator-metal transition and megabar pressure range. (orig.)