1. National Mineral Resources University “Gorniy,” St. Petersburg 199106, Russia
2. West Virginia University, Morgantown, West Virginia 26506, USA
3. St. Petersburg State University, St. Petersburg 199034, Russia
4. University ITMO, Kronverkskiy pr. 49, St. Petersburg 197101, Russia
5. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA