München 2019 – scientific programme

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P: Fachverband Plasmaphysik

P 18: Postersitzung

P 18.75: Poster

Thursday, March 21, 2019, 16:30–18:30, Foyer Audimax

Intensity Dependence of the Laser Ionization of Noble Gases — •Matthias Melchger, Dirk Hemmers, Michael Stumpf, and Georg Pretzler — Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität Düsseldorf

Describing the ionization of atoms by intense ultra-short laser pulses requires different theoretical models, depending on the intensity regime. We investigated the intermediate region between the multiphoton and the tunnelling ionization regimes and determined absolute ionization rates for Helium, Neon and Argon over a broad range of laser intensities around 10¹⁵ W/cm². Experiments were conducted using a carefully characterized large capacitor device and yielded the total number of generated free charges. The data evaluation takes into account the intensity variations over the full focal region. The measured numbers are compared to temporally and spatially resolved simulations using the relevant ionization models. Our results allow the prediction of absolute ionization rates in a large range of Keldysh parameters around one.