1. JET Joint Undertaking Abingdon, Oxfordshire, 0X14 3EA, United Kingdom
2. Chalmers University of Technology, Department of Reactor Physics SE-412 96 Göteborg, Sweden (Euratom/NFR Fusion Association)
3. Royal Institute of Technology, Aljvén Laboratory Stockholm, SE-100 44, Sweden (Euratom/NFR Fusion Association)