Identification of magnetic reconnection in the edge region of the RFX plasma

The global 3D magnetic field in the RFX device is reconstructed using Newcomb's solution. We show that the calculation of the current density in toroidal coordinates (as the rotation of the magnetic field) is an efficient tool to identify magnetic structures, such as magnetic islands. It thus is an alternative to field line tracing and Poincare plots, with generally less noise in its results, and with the advantage of allowing to explore straightforwardly structures in 3D space, in contrast to the method of the Poincare plots. In an application, we show how the current density allows to identify a reconnection event, where an m=1, n=7 island chain merges into a single m=0 current-layer.