A Brief Introduction to Space Plasma Physics.pdf - Institute of ...
A Brief Introduction to Space Plasma Physics.pdf - Institute of ...
A Brief Introduction to Space Plasma Physics.pdf - Institute of ...
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• Magne<strong>to</strong>hydrodynamics (MHD)<br />
– The average properties are governed by the basic<br />
conservation laws for mass, momentum and energy in a<br />
fluid.<br />
– Continuity equation<br />
∂n<br />
∂t<br />
s<br />
+ ∇ ⋅ n<br />
– S s and L s represent sources and losses. S s -L s is the net rate<br />
at which particles are added or lost per unit volume.<br />
– The number <strong>of</strong> particles changes only if there are sources<br />
and losses.<br />
s<br />
r<br />
u<br />
– S s ,L s ,n s , and u s can be functions <strong>of</strong> time and position.<br />
– Assume S s =0 and L s =0, ρ s= m<br />
sn<br />
, s ∫ ρ sdr<br />
= M<br />
s where M s is<br />
the <strong>to</strong>tal mass <strong>of</strong> s and dr is a volume element (e.g. dxdydz)<br />
∂M<br />
s<br />
r ∂M<br />
s<br />
r r<br />
+ ∇ ⋅<br />
sus<br />
dr = +<br />
sus<br />
⋅ds<br />
∂t<br />
∫ (ρ )<br />
∂t<br />
∫ ρ<br />
where ds<br />
r is a surface element bounding the volume.<br />
s<br />
=<br />
S<br />
s<br />
−<br />
L<br />
s