The Eart2 - The Earth's Magnetosphere That the interaction...

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The Earth's Magnetosphere That the interaction is supersonic can be seen if we consider first the sound speed in a plasma. This is similar to that in a non-ionised gas: you just need to take account of the fact the protons and electrons may have different temperatures, and you will need to use the ratio of specific heats for ionised Hydrogen (=5/3). The sound speed is given by: where gamma is the ratio of specific heats, T p and T e the proton and electron temperatures, m p and m e their masses, p the pressure, [ro] the density and k Boltzmann's constant. Substituting in the appropriate numbers we find c s is about 60km s -1 , much less than the solar wind speed. Actually, in the case of a plasma we should look at the other wave modes to do this properly.e modes to do this properly. In plasmas the electromagnetic forces change the response of the system to wave propagation and we can study these by looking at the MHD (Magneto- Hydrodynamic) equations. We solve for travelling waves of the type exp(wt-
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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The Eart2 - The Earth's Magnetosphere That the interaction...

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