Progress in Wind-and-React Bi-2212 Accelerator Magnet Technology

Abstract

Abstract-We report on our progress in the development of the technology for the application of Bi2Sr2CaCu2O8+x(Bi-2212) in Wind-and-React accelerator magnets. A series of superconducting subscale coils has been manufactured at LBNL and reacted at the wire manufacturer SWCC. Selected coils are impregnated and tested in self-field, even though the coils exhibited leakage during the partial melt heat treatment. Other coils have been disassembled after reaction and submitted to critical current (Ic) tests on individual cable sections. We report on the results of the current carrying capacity of the coils. Voltage-current (V I) transitions were reproducibly measured up to a quench currents around 1400 A, which is 25% of the expected performance. The results indicate that the coils are limited by the inner windings. We further compare possibilities to use Bi-2212 and Nb3Sn tilted solenoid, and YBa2Cu3O7−δ(YBCO) racetrack inserts to increase the magnetic field in HD2, a 36 mm bore Nb3Sn dipole magnet which recently achieved a bore magnetic field of 13.8 T. The application of Bi-2212 and/or YBCO in accelerator type magnets, if successful, will open the road to higher magnetic fields, far surpassing the limitations of Nb3Sn magnet technology.

Void and phase evolution during the processing of Bi-2212 superconducting wires monitored by combined fast synchrotron micro-tomography and x-ray diffraction

“…At this time the best conventionally processed Bi-2212 wires attain engineering current densities which exceed ∼400 A mm −2 at 4.2 K and 12 T (∼1400 A mm −2 in the superconductor) [4], about a factor of two below Nb 3 Sn conductors for which the superconductor J c can attain 2500-3000 A mm −2 . Whether the Bi-2212 performance limits are still capable of strong enhancement is thus of great interest.…”

“…Fields >30 T are reachable with Bi-2212 magnets [1], which is well beyond the 24 T field limit reachable with Nb 3 Sn magnets. The round wire geometry makes the Bi-2212 conductors especially interesting for high energy physics applications where Rutherford cables are preferred for race track windings [2,3].…”

Bi-2212 round wire development for high field applications

“…High T c superconductor Bi 2 Sr 2 CaCu 2 O 8-x (Bi-2212) wire has demonstrated many attractive features, such as high irreversibility field (B irr > 100 T), isotropic electromagnetic performance, solenoid layer winding, and compatibility with conventional cabling and strand insulation methods. All of these advantages make it easy to adapt the well established Nb 3 Sn technology and make Bi-2212 one of most promising materials to enable superconducting magnets > 25 T range [1][2][3][4][5][6][7][8].…”

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

“…It has been already demonstrated that such properties make Bi-2212 a very competitive conductor for high field applications (> 20 T) such as magnets for nuclear magnetic resonance or accelerators [4][5][6][7][8][9], however, in this context, an enhancement of J C of two or three times seems to be still needed to boost the successful use of this superconductor in such applications. This aim has driven the work of several groups, especially in USA -where, besides the research labs, Oxford Superconducting Technology (OST) is a company leader on Bi-2212 round wire fabrication -and in Japan and Korea.…”