1. Columbia University, New York, New York 10027, USA
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
3. University of California, Irvine, Irvine, California 92697, USA
4. Dipartimento di Energia, Politecnico di Milano, via Ponzio 34/3, I-20133 Milano, Italy
5. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
6. Lawrence Livermore National Laboratory, Livermore, California 94550, USA