hoppe93
commented
2 years ago One could imagine different averages be given. One possible average, which we should support, is the flux surface average of the toroidal current density, $\langle\boldsymbol{j}\cdot\nabla\phi\rangle$, which we can express in terms of the parallel current density evolved in DREAM:
$$\left\langle\boldsymbol{j}\cdot\nabla\phi\right\rangle = \frac{j_\parallel}{B}\left[ G\left\langle\frac{1}{R^2}\right\rangle \right]$$
Given a flux surface-averaged toroidal current density we could therefore obtain the parallel current density in the point of minimum B by inverting this expression:
$$j{\parallel,{\rm min}} = \left\langle\boldsymbol{j}\cdot\nabla\phi\right\rangle\frac{B{\rm min}}{G\left\langle R^{-2} \right\rangle}$$
In DREAM, the current density is to be evaluated at the point of minimum B along each flux surface. It is not uncommon in the fusion community to come across current densities which are averaged over flux surfaces. We should therefore implement support in the recently introduced current density-initialization feature of DREAM to give a flux surface-averaged current density, instead of the current density in the point of minimum B along the flux surface.