Kiel 2004 – wissenschaftliches Programm

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P: Plasmaphysik

P 17: Postersitzung: Plasma-Wand-Wechselwirkung III, Grundlegende Probleme Theorie II, Schwerionen- Laserplasmen II, Dichte Plasmen II

P 17.28: Poster

Mittwoch, 10. März 2004, 17:45–19:30, Foyer

Segregation of neutrals and ions in laser ablated plasmas from binary TiAl targets — •S. N. Srivastava and K. P. Rohr — Fachbereich Physik, Universität Kaiserslautern, Germany

Till now, systematic and differential experiments of laser ablated particle pulses exists only for mono-atomic target systems.The present experiment for the first time compares in detail angular emission characteristics of laser produced plasma pulses ablated from binary material of variable stoichiometry with each other and with those of its pure components. As an example system we have chosen Titanium-Aluminium compounds (TiAl). The plasma was produced by obliquely incident Q-switched laser pulses (EL = 130 mJ, t = 5 ns and l = 1.06 mm) focused to an ablation area of 0.3 mm2. The most remarkable results are: 1. All emission distributions can be well fitted by Gauß-function. 2. The widths of the emission cones of both, ions and total number of particles, steepens as a function of the average atomic mass A and can be well approximated by G = k/A + c. Hereby k systematically depends on the size of the focal area. 3. The width is decreasing with increasing charge state. 4. The direction of the emission turns towards the direction of the incoming laser beam as a function of the particles charge state. The results are of practical interest and give useful datasets for theoretical simulations.