München 2004 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 20: Poster Ultrakurze Lichtimpulse

Q 20.14: Poster

Dienstag, 23. März 2004, 14:00–16:00, Schellingstr. 3

Dense plasma physics studied with XUV-FELs — •Annika Krenz and Jürgen Meyer-ter-Vehn — Max-Planck-Institut für Quantenoptik Garching

We report on the heating of solid matter with the XUV-FEL beams becoming available at DESY in 2004/2005. They will provide 10¹⁴ photons per pulse of 20-200eV energy in 100fs pulses. These beams will generate matter of extremely high energy density with temperatures up to 1keV and pressures in the range of a few hundred Mbar. This corresponds to states of matter found in stellar interiors. A wide range of the phase diagram can be investigated by changing the beam focus and hence the heating intensity. In addition to heating the scattered photons will yield detailed information about the structure of the produced plasma.

The poster will show simulations performed with MULTIfs, a 1D-hydrodynamic code. For laser frequencies close to the plasma frequency the absorption in the target reaches a maximum. This is shown in terms of the temperature and pressure evolution for an intensity of 10¹⁶W/cm² and a photon energy of 30eV. The thickness of the Al-target is 45nm.

Futhermore it is shown that the foil can be used as a femtosecond switch. This is caused by the change of the plasma frequency during heating which may turn an initially transparent foil into an opaque one. Another point is that the plasma spot has defocusing properties. A further unexpected effect is a spatial wave structure seen e.g. in the energy deposited in the target. This structure will lead to ionization layers which exist for a certain time.