NPG Nonlinear Processes in Geophysics NPG Nonlin. Processes Geophys. 1607-7946 Copernicus Publications Göttingen, Germany 10.5194/npg-6-187-1999 Properties of fast solitary structures Ergun R. E. 1 Carlson C. W. 1 Muschietti L. 1 Roth I. 1 McFadden J. P. 1 Space Sciences Laboratory, University of California, Berkeley, CA. 94720, USA 31 12 1999 6 3/4 187 194 Copyright: © 1999 R. E. Ergun et al. 1999 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://npg.copernicus.org/articles/6/187/1999/npg-6-187-1999.html The full text article is available as a PDF file from https://npg.copernicus.org/articles/6/187/1999/npg-6-187-1999.pdf

We present detailed observations of electromagnetic waves and particle distributions from the Fast Auroral SnapshoT (FAST) satellite which reveal many important properties of large-amplitude, spatially-coherent plasma structures known as "fast solitary structures" or "electron phase space holes". Similar structures have been observed in several regions of the magnetosphere including the auroral zone, plasma sheet boundary layer, and bow shock. There has been rapid theoretical progress in understanding these structures. Solitary structures can develop from bidirectional electron beams. Once developed, the one-dimensional properties parallel to the magnetic field can be adequately described by analytical treatment as BGK structures. There remains, however, several unanswered questions. The origin of the bidirectional electron beams, the development of two-or three-dimensional structures, and the observed association with the ion cyclotron frequency are not well understood.