In plasma physics, the Lundquist number (denoted by S) is a dimensionless ratio which compares the timescale of an Alfvén wave crossing to the timescale of resistive diffusion. It is a special case of the magnetic Reynolds number when the Alfvén velocity is the typical velocity scale of the system, and is given by
\( {\displaystyle S={\frac {Lv_{A}}{\eta }},} \)
where L is the typical length scale of the system, \( \eta \) is the magnetic diffusivity and \( v_{A} \) is the Alfvén velocity of the plasma.
High Lundquist numbers indicate highly conducting plasmas, while low Lundquist numbers indicate more resistive plasmas. Laboratory plasma experiments typically have Lundquist numbers between \( {\displaystyle 10^{2}-10^{8}} \), while in astrophysical situations the Lundquist number can be greater than \( 10^{{20}} \). Considerations of Lundquist number are especially important in magnetic reconnection.
See also
Magnetic Reynolds number
References
Priest, Eric; Forbes, Terry (2000), Magnetic Reconnection (PDF), Cambridge University Press, ISBN 978-0-521-48179-3
Hellenica World - Scientific Library
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