报告人：Karoly Osvay教授, University of Szeged

会议时间：2025年07月07日（周一）10:15

会议地点：清河路390号 王大珩厅

报告内容：

Characteristics of ions accelerated in laser plasma depend on the parameters of the irradiating laser pulse especially on its temporal contrast and pulse duration. We have carried out series of systematic experiments to study the dependence of laser-accelerated deuterons on the temporal shape of the laser pulses. The TW peak power, 12 fs laser pulses of the SEA laser in ELI-ALPS exhibit a temporal contrast better than 10¹¹ at the leading edge. A DAZZLER varied both the linear (GDD) and nonlinear chirp (TOD) on a broad range. Two types of ultrathin targets were investigated, both promising for laser-based neutron generation: deuterated foils and heavy water leafs. The cut-off energy of the ions and the maximum total energy of an ion bunch were measured by Thomson ion spectrometers. Contrary to the common belief, the studies revealed that the least cutoff and yield were achieved with transform-limited pulses, while the highest values were obtained with pulses of negative GDD and positive TOD. Moreover, the cutoff energy and the bunch energy of the deuterons reach maximum at different dispersion values. We also proved that the best conditions depend on the target type and thickness. As a direct application of this technique, we have maximized the neutron yield of a laser-based neutron source at 1kHz repetition rate, with the use of the SYLOS3 laser of ELI-ALPS delivering 80mJ, sub-10 fs laser transform limited pulses on an ultrathin heavy water sheet.

Learning from our experiences in ion acceleration and from laser development accumulated over decades, we may address the evergreen question: what are the most important parameters of a laser pulse for applications?

报告人简介：

Karoly Osvay (PhD 1995, Habil 2011, University of Szeged) has worked on generation, diagnostics, and amplification of ultrashort peak power laser pulses and their applications in material processing, time-resolved spectroscopy and ion acceleration. He spent more than eight years in top research laboratories such as Central Laser Facility, UK, Lund University, Sweden and Max Born Institute, Germany. In 1998, as an associate professor, he founded the TeWaTi laboratory at the University of Szeged, which hosted the first terawatt peak power laser system in Central-East Europe. For more than a decade, he was also the deputy head and later head of the Department of Optics and Quantum Electronics at the University of Szeged. After joining the ELI program in 2007, he worked in the management of the ELI Preparatory Phase led by Gerard Mourou between 2008 and 2010. When the Hungarian ELI project started in 2010, he coordinated and managed the implementation of ELI-ALPS as its founding Research Technology Director, and Head of Laser Division, positions he held until 2019. Since then, he has been the Head and the Principal Investigator of the National Laser Initiated Transmutation Laboratory at the University of Szeged, established by the Hungarian government to develop a laser-driven neutron source for nuclear applications.