1. Institute of Plasma Physics and Laser Microfusion, Hery 23 St. 01-497 Warsaw, Poland
2. Institute of Physics, Opole University, ul. Oleska 48, 45-052 Opole, Poland
3. Max-Planck-Institut fürPlasmaphysik, Wendelsteinstrasse 1, 17491 Greifswald, Germany
4. CEA, IRFM, F-13108 Saint-Paul-Lez-Durance, France