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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• Maxwell’s equations in integral form r 1 ∫ E ⋅ ndA ˆ = ∫ ρ dV A ε 0 – A is the area, dA is the differential element of area – nˆ is a unit normal vector to dA pointing outward. – V is the volume, dV is the differential volume element ˆn ' ∫ ∫ A C r B ⋅ nd ˆ A = v r E ⋅ ds = − 0 r ∂B ∂t ' ⋅nˆ dF = − ∂Φ ∂ t – is a unit normal vector to the surface element dF in the direction given by the right hand rule for integration around C, and is magnetic flux through the surface. ds r Φ – is the differential element r around C. r r ∂E ' ∫ B ⋅ds = 2 n dF J C c ∫ ⋅ ˆ + µ 0 ∂t ∫ ∫ 1 ˆ ' ⋅n dF

• The first adiabatic invariant r ∂B r – = −∇× E says that changing B r drives E r (electromotive ∂t force). This means that the particles change energy in changing magnetic fields. – Even if the energy changes there is a quantity that remains constant provided the magnetic field changes slowly enough. – µ is called the magnetic moment. In a wire loop the magnetic moment is the current through the loop times the area. µ 1 2 2 mv = ⊥ = B – As a particle moves to a region of stronger (weaker) B it is accelerated (decelerated). const.

• Maxwell’s equations in integral form<br />

r 1<br />

∫ E ⋅ ndA ˆ = ∫ ρ dV<br />

A<br />

ε 0<br />

– A is the area, dA is the differential element <strong>of</strong> area<br />

– nˆ is a unit normal vec<strong>to</strong>r <strong>to</strong> dA pointing outward.<br />

– V is the volume, dV is the differential volume element<br />

ˆn '<br />

∫<br />

∫<br />

A<br />

C<br />

r<br />

B ⋅ nd ˆ A =<br />

v r<br />

E ⋅ ds = −<br />

0<br />

r<br />

∂B<br />

∂t<br />

'<br />

⋅nˆ<br />

dF = −<br />

∂Φ<br />

∂ t<br />

– is a unit normal vec<strong>to</strong>r <strong>to</strong> the surface element dF in the<br />

direction given by the right hand rule for integration around<br />

C, and is magnetic flux through the surface.<br />

ds<br />

r<br />

Φ<br />

– is the differential element<br />

r<br />

around C.<br />

r r ∂E<br />

'<br />

∫ B ⋅ds<br />

= 2 n dF J<br />

C<br />

c ∫ ⋅ ˆ + µ<br />

0<br />

∂t<br />

∫<br />

∫<br />

1<br />

ˆ<br />

'<br />

⋅n dF

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