A New Design for the Superconducting Outsert of the GHMFL 42+ T Hybrid Magnet Project

Abstract

A new superconducting coil outsert has been designed to be integrated within the existing infrastructure of the GHMFL hybrid project. Based on the novel development of a Nb-Ti Rutherford Cable On Conduit Conductor (RCOCC) cooled at 1.8 K by a bath of superfluid helium at atmospheric pressure, the superconducting coil aims to produce a continuous magnetic field of 8.5 T in a 1.1 m bore diameter. Combined with resistive insert coils, an overall continuous magnetic field of 42+ T will be produced in a 34 mm warm aperture. The main results of the conceptual study are reported including the conductor and coil specifications, the mechanical stress analysis, the coil protection scheme as well as the required cryogenics infrastructure. First developments and tests regarding the RCOCC are also presented.

Final Design of the New Grenoble Hybrid Magnet

“…The most important choices that have been made for the superconducting outsert coil of the new LNCMI hybrid magnet [4] can be summarized as follows: -High current to reduce the inductance of the coil and therefore the voltage levels during quenches, -Nb-Ti/Cu Rutherford cable indirectly cooled by superfluid He at 1.8 K, -Insulated conductors, -Modular coil made of double pancakes, each of them being vacuum impregnated separately. The existing infrastructure of the hybrid magnet has fixed the maximum dimensions of the superconducting coil, which are listed in Table I with the other main parameters.…”

“…The maximum hoop stress for the inner coil turn of 1100 mm diameter is equal to 140 MPa. The new superconducting outsert coil of the Grenoble hybrid magnet is based on an innovative conductor development [4], [5]. A Nb-Ti/Cu Rutherford cable of rectangular cross section is soldered on a Cu-Ag stabilizer to form the so-called Rutherford Cable On Conduit Conductor (RCOCC).…”

Study and Development of the Superconducting Conductor for the Grenoble Hybrid Magnet

“…The superconducting outsert coil, if unshielded, can experience magnetic transients up to 2.3 T/s. To reduce field variations in this faulty operation mode, which can provoke a quench of the superconducting coil, a 30 K copper shield with stainless steel reinforcement was specially developed [4], [6]. It will reduce the maximum field variation down to 0.4 T/s.…”

“…Several hybrid magnets are being built all over the world [2], [3]. A general overview of the Grenoble project can be found in [4] and the final design of the large bore superconducting coil based on Nb-Ti and superfluid He technologies is reported in [5]. This article focuses on the studies and development of the superconducting conductor highlighting the new concept proposed.…”

Quench Simulation of the Hybrid Magnet Superconducting Outsert Being Built in China

“…Steady high magnetic fields above 30 T are commonly generated with purely resistive-insert, water-cooled magnet or hybrid magnet composed of superconducting outsert magnet and resistive-insert magnet [2][3][4][5][6][7][8][9][10]. Compared with the purely water-cooled magnet with the same central magnetic field, the hybrid magnet can save operational costs.…”