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- ItemStable laser-ion acceleration in the light sail regime(College Park : American Institute of Physics Inc., 2013) Steinke, S.; Hilz, P.; Schnürer, M.; Priebe, G.; Bränzel, J.; Abicht, F.; Kiefer, D.; Kreuzer, C.; Ostermayr, T.; Schreiber, J.; Andreev, A.A.; Yu, T.P.; Pukhov, A.; Sandner, W.We present experimental results on ion acceleration with circularly polarized, ultrahigh contrast laser pulses focused to peak intensities of 5×1019 W cm-2 onto polymer targets of a few 10 nanometer thickness. We observed spatially and energetically separated protons and carbon ions that accumulate to pronounced peaks around 2 MeV containing as much as 6.5% of the laser energy. Based on particle-in-cell simulation, we illustrate that an early separation of heavier carbon ions and lighter protons creates a stable interface that is maintained beyond the end of the radiation pressure dominated acceleration process.
- ItemLaser-driven ion acceleration using isolated mass-limited spheres(College Park, MD : Institute of Physics Publishing, 2010) Sokollik, T.; Paasch-Colberg, T.; Gorling, K.; Eichmann, U.; Schnürer, M.; Steinke, S.; Nickles, P.V.; Andreev, A.; Sandner, W.We report on our experiments on laser-driven ion acceleration using fully isolated mass-limited spheres with a diameter down to 8μm for the first time. Two-dimensional (2D) particle-in-cell (PIC) and hydro-code simulations were used to show that the pre-plasma at both the front and rear sides of the target strongly affect the efficiency of the ion acceleration. The mechanism of the plasma flow around mass-limited targets has not yet been identified for laser-driven ion acceleration. Our models indicate that this effect is the cause of the observed limitation to the ion-beam energy in both previous experiments and in our own. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
- ItemParametric study of cycle modulation in laser driven ion beams and acceleration field retrieval at femtosecond timescale(College Park, MD : American Physical Society, 2019) Schnürer, M.; Braenzel, J.; Lübcke, A.; Andreev, A.A.High-frequency modulations appearing in the kinetic energy distribution of laser-accelerated ions are proposed for retrieving the acceleration field dynamics at the femtosecond timescale. Such an approach becomes possible if the laser-cycling field modulates the particle density in the ion spectra and produces quasitime stamps for analysis. We investigate target and laser parameters determining this effect and discuss the dependencies of the observed modulation. Our findings refine a basic mechanism, the target normal sheath acceleration, where an intense and ultrafast laser pulse produces a very strong electrical field at a plasma-vacuum interface. The field decays rapidly due to energy dissipation and forms a characteristic spectrum of fast ions streaming away from the interface. We show that the derived decay function of the field is in accordance with model predictions of the accelerating field structure. Our findings are supported by two-dimensional particle-in-cell simulations. The knowledge of the femtosecond field dynamics helps to rerate optimization strategies for laser ion acceleration.
- ItemA transportable Paul-trap for levitation and accurate positioning of micron-scale particles in vacuum for laser-plasma experiments(Melville, NY : American Institute of Physics, 2018) Ostermayr, T.M.; Gebhard, J.; Haffa, D.; Kiefer, D.; Kreuzer, C.; Allinger, K.; Bömer, C.; Braenzel, J.; Schnürer, M.; Cermak, I.; Schreiber, J.; Hilz, P.We report on a Paul-trap system with large access angles that allows positioning of fully isolated micrometer-scale particles with micrometer precision as targets in high-intensity laser-plasma interactions. This paper summarizes theoretical and experimental concepts of the apparatus as well as supporting measurements that were performed for the trapping process of single particles.
- ItemVerbundvorhaben: Forscherverbund: Vordringliche Massnahme zu Laser- und Entladungsbasierten EUV-Strahlquellen, Teilvorhaben Konversionsuntersuchungen für laserbasierte Quellen im EUV-Bereich in Abhängigkeit von relevanten Laserparametern : Abschlussbericht(Berlin : Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 2001) Nickles, P.V.; Stiel, H.; Vogt, U.; Will, I.; Ter-Avetisyan, S.; Schnürer, M.; Sandner, W.[no abstract available]