Nonlinear Phenomena in Microphysics of Collisionless Plasmas. Application to Space and Laboratory Plasmas
J. Phys. IV France 05 (1995) C6-43-C6-48
Ion Sound Solitary Waves with Density DepressionsR.A. Cairns1, R. Bingham2, R.O. Dendy3, C.M.C. Nairn4, P.K. Shukla5 and A.A. Mamun1
1 School of Mathematical and Computational Sciences, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, U.K.
2 Space Science Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, U.K.
3 UKAEA, Government Division, Fusion, Culham, Abingdon, Oxfordshire, OX14 3DB, U.K.
4 Swedish Institute of Space Physics, Box 812, 98128 Kiruna, Sweden
5 Institut für Theoretische Physik 4, Ruhr-Universität Bochum, 44780 Bochum, Germany
We show that a non-thermal electron distribution may change the nature of ion acoustic solitons. If the ions are assumed to respond as a fluid to perturbations in the potential, with no significant trapping in a potential well, then a thermal plasma only supports a solitary waves with a density peak. However, with a suitable distribution of non-thermal particles, solitary waves with both density peaks and density depressions may coexist. This may have applications to magnetosperic observations, where solitary structures with lowered densities have been observed in regions where the electron distribution is also seen to be non-thermal.
© EDP Sciences 1995