2001 II 6A

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The Alfven velocity is:

v_{A}=\frac{B}{\sqrt{4\pi n_{i}m_{i}}}

The ion sound speed is:

v_{s}=\sqrt{ZT_{e}/m_{i}}

So that if vA˜vs:

\frac{B^{2}}{4\pi n_{i}m_{i}}\sim\frac{ZT_{e}}{m_{i}}

Then:

\frac{B^{2}}{4\pi n_{i}ZT_{e}}\sim1

By quasineutrality niZ = ne:

\frac{B^{2}}{4\pi n_{e}T}\sim1

Since β = 8πnT / B2:

β˜2

For the ion acoustic wave to have landau damping:

vs˜vTi

Plugging in:

\sqrt{\frac{ZT_{e}}{m_{i}}}\sim\sqrt{\frac{T_{i}}{m_{i}}}

Or:

\frac{ZT_{e}}{T_{i}}\sim1

This page was recovered in October 2009 from the Plasmagicians page on Generals_2001_II_6A dated 19:47, 25 April 2007.

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