Collisionality: Difference between revisions

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Consider a test particle with charge ''q'', mass ''m'', and velocity ''v'' colliding with bulk particles with charge ''q*'', mass ''m*'', and thermal velocity ''v*''. Then the collision frequency ''&nu; = 1/&tau;<sub>coll</sub>'' is given by
Consider a test particle with charge ''q'', mass ''m'', and velocity ''v'' colliding with bulk particles with charge ''q*'', mass ''m*'', and thermal velocity ''v*''. Then the collision frequency ''&nu; = 1/&tau;<sub>coll</sub>'' is given by
<ref>K. Miyamoto, ''Plasma Physics and Controlled Nuclear Fusion'', Springer-Verlag (2005) ISBN 3540242171</ref>
<ref>K. Miyamoto, ''Plasma Physics and Controlled Nuclear Fusion'', Springer-Verlag (2005) {{ISBN|3540242171}}</ref>


:<math>\nu = \left ( \frac{qq^*n^*}{\varepsilon_0 m}\right )^2 \frac{\ln \Lambda}{4\pi (m_r/m)v^3n^*}</math>
:<math>\nu = \left ( \frac{qq^*n^*}{\varepsilon_0 m}\right )^2 \frac{\ln \Lambda}{4\pi (m_r/m)v^3n^*}</math>
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:<math>\nu^* = \frac{\rm connection~length}{\rm trapped~particle~mean~free~path}</math>
:<math>\nu^* = \frac{\rm connection~length}{\rm trapped~particle~mean~free~path}</math>


See [[Connection length]].
See [[Connection length]]. The mean free path is estimated by the thermal velocity divided by the collision frequency, ''v<sub>th</sub> / &nu;''.


== References ==
== References ==
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