Magnetic probe system on JT-60

We have constructed a data processing system for magnetic probes on JT-60. The signal to noise ratio achieved is over 500 for output signals as a result of the careful calibrations. This system can be used for the off-line calculation of plasma parameters such as plasma positions, Shafranov lambda, etc. MHD fluctuations are also measured. The m =3 fluctuations in the peripheral region with the same frequency of SX and FIR signals are observed. The magnetic fluctuations just prior to the disruptions were measured effectively using the pretrigger function.