1. LPC2E/CNRS - University of Orleans, 3A Avenue de la Recherche Scientifique, F-45071 Orleans Cedex, France
2. Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
3. CEA, DAM, DIF, F-91297 Arpajon Cedex, France
4. Department of Mechanical Engineering, Temple University, Philadelphia, Pennsylvania 19122, USA