Nb_3Sn coil R&D of a superconducting sextupole magnet for neutron refractive optics device

摘要

A Nb_3Sn coil for a superconducting sextupole magnet with 40 mm in bore diameter to be used as a neutron refractive optics device was manufactured. The length of the coil is 1 m and the thickness is 23 mm with the saddle shape at the ends. The suspended angle of the coil is 20°. The current 930 A was achieved at 4.2 K and the current density was 1189 A/mm~2. The strength of the magnetic field gradient G = 2B(r)/r~2 (r: distance from the center axis of the sextupole magnet) at this current is estimated to be 21,000 T/m~2.