Lundquist number

Lundquist number

In plasma physics, the Lundquist number (denoted by S) is the dimensionless ratio of an Alfvén wave crossing timescale to a diffusion timescale. In SI units, it is given by:Sequivfrac{mu_0LV_A}{eta},where L is a typical length scale, mu_0 is the permeability of free space, V_A=frac{B}{sqrt{mu_0 ho is the Alfvén speed, and eta is the plasma resistivity. High Lundquist numbers indicate highly conducting plasmas, while low Lundquist numbers indicate more resistive plasmas. Laboratory plasma experiments typically have Lundquist numbers between 50-10^8, while in astrophysical situations the Lundquist number can be greater than 10^{20}. Considerations of Lundquist number are especially important in magnetic reconnection.

References

* Eric Priest, Terry Forbes, "Magnetic Reconnection", Cambridge University Press 2000, ISBN 0521481791, [http://assets.cambridge.org/0521481791/sample/0521481791WSN01.pdf contents and sample chapter online]


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