“…In presence of smaller magnetic fields, Faraday rotation measurements are still possible, but they require the use of a small birefringent crystal placed within the plasma to increase the rotation. Magneto-optical probes, relying on this enhancement of the Faraday rotation, have been tested with large current-driven magnetic fields [19][20][21]. However, to our knowledge, they have not yet been used to measure smaller fluctuating magnetic fields within a plasma, nor tested against other diagnostics methods.…”