HR: 14:10h
AN: NG33A-03    [Abstracts]
TI: Nonlinear Mirror Waves in Space Plasmas
AU: Pokhotelov, O A
EM: o.a.pokhotelov'sheffield.ac.uk
AF: Centre for Signal Processing and Complex Systems, The University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom
AU: Sagdeev, R Z
EM: rsagdeev@gmail.com
AF: Department of Physics,The University of Maryland, College Park, College Park, MD 20740, United States
AU: * Balikhin, M A
EM: m.balikhin@sheffield.ac.uk
AF: Centre for Signal Processing and Complex Systems, The University of Sheffield, Mappin Street, Sheffield, S1 3JD, United Kingdom
AB: A unified theory of finite-amplitude mirror type waves in non-Maxwellian space plasmas is developed. The collisionless kinetic theory in a guiding center approximation, modified for accounting the effects of the finite ion Larmor radius effects, is used as the starting point. The model equation governing the nonlinear dynamics of mirror waves near instability threshold is derived. In the linear approximation it describes the classical mirror instability with the linear growth rate expressed in terms of an arbitrary ion distribution function. In the nonlinear regime the mirror waves form solitary structures that have the shape of magnetic holes. The formation of such structures and their nonlinear dynamics has been analyzed both analytically and numerically. The main nonlinear mechanism responsible for mirror instability saturation is associated with modification (flattening) of the shape of the background ion distribution function in the region of small parallel particle velocities. The width of this region is of the order of the particle trapping zone in the mirror hole. Near the mirror instability threshold the saturation arises before its width reaches the ion thermal velocity. The nonlinear mode coupling effects in this approximation are smaller and unable to take control over evolution of the space profile of saturated mirror waves or lead to their magnetic collapse. This results in the appearance of quasi-stable solitary mirror structures having the form of deep magnetic depressions. The relevance of the theoretical results to recent satellite observations is stressed.
DE: 7839 Nonlinear phenomena (4400, 6944)
DE: 7852 Solitons and solitary waves (4455)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting