Relaxation of Trapped Magnefic Field in a Bi-2212/Ag Solenoidal Coil with Persistent Current Switch

We succeeded in the persistent current mode operation of a small Bi2Sr2Ca1Cu2O x (Bi-2212) solenoidal coil with persistent current switch (PCS). The coil and the PCS were fabricated using silver sheathed Bi-2212 multifilamentary tape. We confirmed the ability to trap a 1000 G magnetic field with a persistent current of 30 A. From the relaxation of persistent current up to 50 h, a relaxation time was estimated to be τ>800 ks, showing a resistance in overall current loop below 0.2 n Ω. The average rate of magnetic relaxation was 0.4%/h with a inductance L of 0.2 mH. The relaxation was able to explain by means of the thermally assisted flux creep model. The pinning potential U 0 was estimated from the relaxation curve to be 6 meV.