1. Institut für Plasmaphysik, Forschungszentrum Jülich GmbH EURATOM Association, Trilateral Euregio Cluster, D-52425 Jülich, Germany
2. Laboratory for Plasma Physics, Ecole Royale Militaire - Koninklijke Militaire School, Association EURATOM-Belgian State, Trilateral Euregio Cluster B-1000 Brussels, Belgium
3. Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM Trilateral Euregio Cluster, P.O. Box 1207, NL-3430 BE Nieuwegein, The Netherlands