Nanoplasma dynamics in laser irridiated clusters |
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| Thomas Fennel | |
| Universität Rostock | |
| The continuing interest in intense laser cluster interactions is driven by both technological applications and the quest for fundamental insight into complex many-body processes. The highly efficient absorption of laser energy and subsequent emission of fast electrons, energetic highly charged ions, x rays, and neutrons is relevant for the generation of EUV light, energetic particles, and pulsed neutrons bursts. The created nanoplasma itself is of fundamental interest for studying strong-field-induced correlated dynamics in dense media as the microscopic processes are also of key importance to other branches of many-body physics, including plasma physics, and laser modification of solids, such as dielectrics.
Much of the violent cluster response is related to the creation of a hot transient nanoplasma. In the talk two central aspects of the nanoplasma dynamics will be addressed. First, laser excitation of a temporarily resonant collective electron mode results strongly enhanced absorption and production of energetic electrons. Second, experiments show that intermediate and heavy atom clusters emit ions with charge states up to 20–30 for moderate laser intensities of 10^14 - 10^15} W/cm^2. The mechanisms underlying the generation of these highly charged ions remain debated. Our investigations support, that local-field effects on electron-impact ionization (EII) as well as the electron-ion recombination dynamics in the exploding clusters have to be considered in detail to explain the observed highly charged ions. By taking both effects into account in molecular simulations a much better agreement with experiments is achieved when compared to previous studies. Local-field enhanced EII an frustrated electron-ion recombination together can augment the highest charge states by more than a factor of two, when compared to the conventional treatment of EII and total recombination of all quasi-free electrons. |