Stability for Ag sheathed Bi2Sr2CaCu2O8 tape coils under strong electromagnetic force state

We made a AgMg/Bi2212 magnet for investigation of the mechanical and superc onducting properties under the large electromagnetic stress. The coil was r einforced by the cowinding technique with Hastelloy tapes. The strain value s at the operation current of 275 A was about 0.25% for a coil reinforced b y one Hastelloy tape but 0.1% for that reinforced by three Hastelloy tapes. In addition, the rapid increase of voltage was observed, when the operatio n current reaches to 275 A. The stability of the test magnet is discussed.