[1] Inst Plasma Phys, Dept Pulse Plasma Syst, Vvi, Slovankou 3, Prague 18200, Czech Republic
[2] Masaryk Univ, Fac Sci, Dept Phys Elect, Kotlarska 2, CS-61137 Brno, Czech Republic
[3] Charles Univ Prague, Fac Math & Phys, V Holesovickach 2, CR-18000 Prague, Czech Republic
[4] Leibniz Inst Plasma Sci & Technol, Felix Hausdorff Str 2, D-17489 Greifswald, Germany
[5] EMPA Swiss Fed Labs Mat Sci & Technol, St Gallen, Switzerland
[6] Stevens Inst Technol, Dept Phys & Engn Phys, Hoboken, NJ 07030 USA