1. Department of Pulse Plasma Systems, Institute of Plasma Physics, Czech Academy of Sciences, Za Slovankou 3, 182 00 Prague, Czech Republic
2. Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague, Czech Republic
3. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague, Czech Republic