1. Plasma Phenomena and Chaos Laboratory, Semiconductor Physics Institute, A. Goštauto 11, Vilnius 01108, Lithuania
2. Department of Physics, Faculty of Fundamental Sciences, Vilnius Gediminas Technical University, Saulėtekio 11, Vilnius 10223, Lithuania
3. Department of Radiophysics, Faculty of Physics, Vilnius University, Saulėtekio 9, Vilnius 10222, Lithuania