[1] Politecn Torino, Ist Nazl Fis Mat, Turin, Italy
[2] Politecn Torino, Dipartimento Energet, Turin, Italy
[3] MIT, Plasma Sci & Fus Ctr, Cambridge, MA 02139 USA
[4] Assoc Euratom ENEA CNR, Ist Fis Plasma, Milan, Italy
[5] Ecole Polytech Fed Lausanne, Assoc Euratom Confederat Suisse, Ctr Rech Phys Plasmas, CH-1007 Lausanne, Switzerland
[6] Assoc Euratom ENEA Fus, Ctr Ric Energia Frascati, Frascati, Italy
[7] Univ Pisa, Ist Nazl Fis Mat, Pisa, Italy
[8] Univ Pisa, Dipartimento Fis, Pisa, Italy
[9] CEA Cadarache, Dept Rech Fus Controlee, St Paul Les Durance, France
[10] Univ Texas, Inst Fus Studies, Austin, TX 78712 USA
[11] Univ Lecce, Dipartimento Math, I-73100 Lecce, Italy