1. University of Bucharest, Faculty of Physics, 077125 Magurele-Ilfov, Romania
2. Horia Hulubei National Institute for Physics and Nuclear Engineering, 077126 Magurele-Ilfov, Romania
3. National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele-Ilfov, Romania
4. Department of Engineering, School of Technology, Reykjavik University, Menntavegur 1, IS-102 Reykjavik, Iceland
5. Research Institute of the University of Bucharest (ICUB), 90 Panduri Street, 050663 Bucharest, Romania