Lundquist number

Template:Short description 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

$S=\frac{L{v}_A}{\eta },$

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 $10^2-10^8$, 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 Prandtl number
• Péclet number
• Stuart number

References

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