1. FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands
2. Ioffe Institute, RAS, Saint Petersburg, 194021, Russia
3. MultiTech Ltd., Saint Petersburg, 198103, Russia
4. Institut für Plasmaphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany