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P: Fachverband Plasmaphysik
P 5: Sonstiges
P 5.1: Talk
Monday, March 30, 2009, 17:30–17:45, INP-Staffelgeschoß
Relativistic laser-plasma intensity measurement by nuclear-activation based diagnostics — •Marc Günther1, Karsten Vogt2, Kerstin Sonnabend1, Erik Brambrink3, Knut Harres1, Ina Alber1, Anke Otten1, Jörg Schütrumpf1, Klaus Witte2, and Markus Roth1 — 1TU Darmstadt - Institut für Kernphysik, Darmstadt, Germany — 2GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany — 3Ecole Polytechnique - LULI, Palaiseau, France
The recent progress in ultra-intense lasers induces focused intensities (I > 10^19 W/cm^2) in the highly relativistic regime. During the laser-solid interaction for such high intensities, an intense relativistic electron current is injected from the plasma created on the laser focal spot inside the target. The laser absorption and the laser peak intensity during the laser-solid interaction are still unknown. The measurement of the laser peak intensity within the relativistic range with conventional techniques is not directly possible, mainly because the laser intensity is determined by the laser-plasma interaction itself.
In order to determine the "temperature" of the hot electron distribution by nuclear pyrometry we use novel activation targets as a kind of calorimeter consisting of a composition of several isotopes with different photon-neutron disintegration cross sections in the preferred (g,n) reaction type. The consequence is a relatively high reaction yield for a wide range of photon energies. The determination of the relativistic electron distribution in a wide range of laser intensities will be possible.