Author Affiliations

G. M. H. Knippels,^#,*,** D. Ocpts,^#,*,** A. F. G. van der Meer,^#,*,** T. Nie,^* A. M. MacLeod,^* W. A. Gillespie,^* D. Simanovski,^** T. I. Smith,^** and H. A. Schwcttman^**

^#FOM-Institute for Plasma physics, Edisonbaan 14, 3439 MN, Nieuwegein, The Netherlands

^*School of Science and Engineering, University of Abertay Dundee, Dundee, DD1 1HG, U.K.

^**Stanford Picosecond Tree-Electron Laser Center, W W. Hansen Experimental Physics laboratory, Stanford University, Stanford, California 94305-4085, USA