Resistive skin time

The resistive skin time is a characteristic time of typical magnetohydrodynamic (MHD) phenomena.

Definition
The resistive skin time is defined as: $$\tau_R=\frac{\mu_0 a^2}{\eta}$$ where $$\eta$$ is the resistivity, $$a$$ is a typical radius of the device and $$\mu_0$$ is the magnetic permeability.