Kinetic theory of plasma discontinuities

The plasma universe has a cellular structure [Alfvén, 1981]: broad regions where fluid-like plasma theory applies are separated by thin boundaries where fluid theory fails and where a full kinetic description is required. These boundary layers separate plasmas possessing drastically different parameters and are due to sheets of electric currents. Space exploration has shown that such current layers are formed at many places throughout the heliosphere, and by inference throughout the Universe.

Investigation of plasma processes within such layers are important as these processes control the mass and energy exchange between adjacent regions. For instance, processes at the Earth's magnetopause control the overall dynamics of the magnetosphere, e.g., phenomena like magnetospheric substorms and aurora. 

Different types of boundary layers may form in space plasmas [Hudson, 1970] A common type is classified as tangential discontinuity (TD). This type of discontinuity describes a structure where the magnetic field and the flow are tangential to the boundary surface.

Much of the theoretical work at the Belgian Institute for Space Aeronomy (BIRA-IASB) has focussed on such TD layers. In particular, Vlasov equilibrium models of TDs have been developed and analyzed in detail. 




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