Space physics EF2245 Tomas Karlsson Space and Plasma Physics School of Electrical Engineering EF2245 Space Physics 2010

Space physics EF2245 EF2245 Space Physics 2010 Course goals After the course the student should be able to describe and explain basic processes in space plasma physics use established theories to estimate quantitatively the behaviour of some of these processes make simple analyses of various types of space physics data to compare with the quantitative theoretical predictions describe some hot topics of today’s space physics research Litterature Kivelson, M.G., and C. T. Russel (ed.), Introduction to Space Physics, Cambridge Univeristy Press. Boström, R., Electrodynamics of the Ionosphere, in Cosmical Geophysics, Ed. Egeland et al. Lyons, L., Formation of Auroral Arcs via Magnetosphere-Ionosphere Coupling, Reviews of Geophysics, 30, 2, , 1992.

Do you know MatLab? EF2245 Space Physics 2010

 L L x d Plasma frequency

Single particle motion EF2245 Space Physics 2010 Consider a charged particle in a magnetic field. y x B = B z z + Assume an electric field in the x-z plane: Constant acceleration along z

Drift motion EF2245 Space Physics 2010  Average over a gyro period: In general:

Drift motion F = 0 F = qE F = mg F = -  grad B EF2245 Space Physics 2010

Maxwell’s equations Gauss’ law No magnetic monopoles Faraday’s law Ampére’s law Lorentz’ force equation Ohm’s law j Energy density EF2245 Space Physics 2010

Frozen in magnetic flux PROOF II A B Order of magnitude estimate: Magnetic Reynolds number R m : R m >> 1  R m << 1  Frozen-in fields! Diffusion equation! EF2245 Space Physics 2010

This together with mass conservation, two of Maxwell’s equations and Ohm’s law make up the most common MHD equations: Magnetohydrodynamics (MHD) (1) (3) (4) Only consider slow variations (5) EF2245 Space Physics 2010 v (2)

Magnetohydrodynamics (MHD) (1) In equilibrium: Represents tension along B If magnetic tension = 0 Magnetic pressure EF2245 Space Physics 2010

Solar wind EF2245 Space Physics 2010 Solar corona

Solar wind properties EF2245 Space Physics 2010

Solar wind properties EF2245 Space Physics 2010

Solar wind properties 1.4∙ ∙ ∙ ∙ P interstellar  – Pa EF2245 Space Physics 2010

Critical radius for realistic temperatures EF2245 Space Physics 2010

Solar wind solutions EF2245 Space Physics 2010