Plasma current density

Using Ampère's law, the current density can be written in terms of the magnetic field as

$$\mu_0 \mathbf{J}= \nabla \times \mathbf{B}= - \frac{\partial B_{\... ... \frac{\partial B_Z}{\partial R} \right) \hat{\ensuremath{\boldsymbol{\phi}}} .$$ (36)