A 1.2 T canted cosθ dipole magnet using high-temperature superconducting CORC^® wires

Abstract

REBa 2 Cu 3 O x (REBCO, RE = rare earth elements) coated conductors can carry high current in high background fields, in principle enabling dipole magnetic fields beyond 20 T. Although model accelerator magnets wound with single REBCO tapes have been successfully demonstrated, magnet technology based on high-current REBCO cables for high-field accelerator magnet applications has yet to be established. We developed a two-layer canted cos θ dipole magnet with an aperture of 70 mm using 30 m long commercial Conductor on Round Core (CORC R) wires. The 3.1 mm diameter CORC R wire contained 16 commercial REBCO tapes with a 30-µm thick substrate. The magnet was tested at 77 and 4.2 K. It generated a peak dipole field of 1.2 T with 4.8 kA at 4.2 K with neither thermal runaway nor training. Reasonable geometric field quality and strong magnetization-current effects with multipole decay were observed. Our work demonstrated a feasible high-temperature superconducting magnet technology as a first step toward a new accelerator magnet paradigm that will enable high-field inserts for next-generation circular colliders and stand-alone magnets that can operate over a wide temperature range for a broad range of applications.

Small REBCO isotropic round wire (STAR): an important step from performant material to practical conductor in high field HTS magnets

“…Wire #2, cooled at the liquid helium temperature of 4.2 K, exhibits a record (for an isotropic cable) J e =of 438 A mm −2 under a 20 T field when bent with a curvature radius as small as 15 mm. This value is similar to what has been reported recently for the CORC [8] and enables the wire to be used for accelerator magnets of any type, like a cosϑ layout and especially a canted cosine theta layout [13]. The paper also mentions the mechanical degradation induced with repeated current cycles and pulsed current cycles (pulsed current is used to avoid overheating), in a 'dry', very high current (eight layers) wire.…”

Dipole Magnets above 20 Tesla: Research Needs for a Path via High-Temperature Superconducting REBCO Conductors

“…Based on the experience from C0, we developed the C1 magnet that is identical with C0a except with 40 turns of conductor. C1 reached a dipole field of 1.2 T with 4.8 kA at 4.2 K, consistent with the design target [187]. The field quality of a CORC R CCT dipole magnet was measured for the first time.…”

“…If a low electrical contact resistance is required (Section 3.4), would it lead to pronounced dynamic field errors that depend on the current ramp rates as observed in LTS magnets [181][182][183][184][185][186]? Measurements from recent Roebel and CORC R dipole magnets show no pronounced dynamic field errors [174,187]. More measurements on magnets and cables preferably with different R c will be useful to address the question [188,189].…”

“…Second, the winding of C1 magnet demonstrated an option suitable for automated winding of longer magnets (Section 3.1). During the winding of C1, the conductor spool rotated around the mandrel like winding a solenoid magnet [187]. The opening of the grooves follows the plane determined by the local tangent of normal vectors of the CCT curve in the Frenet-Serret frame [215].…”

Effect of monotonic and cyclic axial tensile stress on the performance of superconducting CORC® wires

“…Each tape layer was wound with opposite pitch from its neighboring layers. The CORC ® wire layouts are identical to those currently developed for CORC ® -based canted cosine-theta accelerator magnets [25,26]. The CORC ® wires were wound at lengths of several meters, after which each sample specimen was cut at a length of about 0.5 m. Copper tube terminals, 6.38 mm in diameter and 0.15 m in length, were mounted at both ends of the samples [24] and filled with 63Sn37Pb solder.…”