Fig. 9: Forward model schematics. Magnets, plasma, and vessel currents are represented by multiple axisymmetric current carrying elements with constant current density.
From: Generation of field-reversed configurations via neutral beam injection

There are 8 arrays of 8 azimuthal Mirnov probes measuring the three magnetic field components plus 30 diamagnetic loops located outside the plasma. Additional flux loops and Bz probes are located outside the vessel.