Development of Interaction Region Superconducting Magnet Twin-Aperture Final Focus Quadrupole Prototype for Super Tau-Charm Facility

Super Tau Charm Facility (STCF) is the third generation e+-e- collider under design and R&D with a circumference about 860 m, a center-of-mass (CoM) energy range from 2 to 7 GeV. The facility has design luminosity higher than 0.5×1035cm-2s-1, about 100 times higher than BEPC-II. It will provide a factory producing massive tau leptons and charm hadrons, to unravel the mystery of how quarks form matter and the symmetries of fundamental interactions. To squeeze the beam for higher luminosity, compact twin-aperture high gradient interaction region superconducting magnet (IRSM) systems are required on both sides of interaction point (IP). There are two twin-aperture superconducting quadrupoles, QD1 and QF2, in each IRSM, with design field gradients of 50 T/m and 40 T/m, respectively, and sited at a beam crossing angle of 60 mrad. Besides quadrupoles, each of the two IRSMs also consists of anti solenoids (including screen solenoids and compensation solenoids) and orbit correctors. In this paper, technical considerations and full-size prototype designs of the first quadrupole coils QD1 are described.