Effects of conductor anisotropy on the design of Bi Sr Ca Cu O sections of 25 T solenoids

Abstract

The development of a 25 T superconducting magnet is usually envisioned with the use of an innermost coil wound with high-temperature superconductor (HTS) material. At present, Bi2Sr2CaCu2Ox and Bi2Sr2Ca2Cu3Ox (BSCCO) conductors are the only candidate conductors available with sufficient length and current carrying capability. Unlike NbTi and Nb3Sn conductors, the BSCCO crystal structure and thus properties are strongly anisotropic. In conductor form, various degrees of anisotropy occur. It is often assumed that this anisotropy simply implies that radial field components must be minimized. We show that this assumption can be misleading. Using the average grain colony misalignment angle to parameterize the anisotropy, three regimes are distinguished in the relationship between average grain colony misalignment and critical current limiting field components. The implications of these separate regimes on the design process for 25 T superconducting magnet design are discussed.

The generation of 25.05 T using a 5.11 T Bi2Sr2CaCu2Oxsuperconducting insert magnet

“…To first order, the axial height of the HTS insert coil is then a tradeoff between the height required in a solenoid to approach the infinite-solenoid limit, and the increasing radial field in the LBRM with increasing vertical distance from the centre of the magnet. Thus, the axial dimension of each section is determined using a projected current density considering the anisotropy of the conductor in combination with the total field strength and field angle [15]. Typical field dependence of the critical current, for field perpendicular to the flat side of the tape (i.e.…”

Field Dependence of the Critical Current and Its Relation to the Anisotropy of BSCCO Conductors and Coils

“…The field components are calculated using the actual dimensions and current densities in the double pancakes and background magnet. The latter is described in [6]. The electric field along the conductor is calculated using 3where is the criterion, the operating current, the assumed short-sample conductor self-field and the index of transition.…”

Angular Dependence of Critical Current in Coated Conductors at 4.2 K and Magnet Design

“…In a magnet, the magnetic field at the coil ends has a component perpendicular to the tape wide face, and the angle can reach values close to 10 degrees [1] in the innermost coil. Depending on the magnet design, the reduction of the critical current can compromise the performances of the superconducting coil.…”