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K: Fachverband Kurzzeitphysik
K 5: Laserstrahlwechselwirkung und Laseranwendungen
K 5.2: Talk
Tuesday, February 26, 2013, 14:15–14:30, HS 4
Ultrasmall divergence of laser-driven ion beams from nanometer thick foils — •jianhui bin1,2, wenjun ma1,2, klaus allinger1,2, hongyong wang3, daniel kiefer1,2, sabine reinhardt1, peter hilz1, konstantin khrennikov1,2, stefan karsch1,2, xueqing yan3, ferenc krausz1,2, toshiki tajima1, dieter habs1,2, and joerg schreiber1,2 — 1Faculty of Physics, Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, 85748 Garching, Germany — 2Max Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany — 3State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
We report on experimental studies of divergence of proton beams from nanometer thick diamond- like carbon (DLC) foils irradiated by an intense laser with high contrast. Proton beams with extremely small divergence (half angle) of 2 degree are observed in addition with a remarkably well- collimated feature over the whole energy range, showing one order of magnitude reduction of the divergence angle in comparison to the results from μm thick targets. We demonstrate that this reduction arises from a steep longitudinal density gradient and an exponentially decaying transverse profile at the rear side of the ultrathin foils. Agreements are found both in an analytical model and in particle-in-cell simulations. Those novel features make nm foils an extremely attractive alternative for high flux experiments relevant for fundamental research in nuclear and warm dense matter physics.