New coil configurations with 2G-HTS and benefits for applications

Abstract

A scalable concept to prepare high current density windings with high-temperature superconducting material is introduced. The concept covers miniaturized high-current windings and large coils for applications in energy technology as well. The principle is based on a circular disk-up-down-assembly ('DUDA') and extended to rectangular coils. First measurements on the assemblies (≈40 turns) in liquid nitrogen are presented as a proof-of-concept. Centre fields of ≈40 mT and ≈340 mT are measured during steady operation and pulsed operation respectively. Operating the assemblies at lower temperatures will strongly increase the current and field performance. Lowering the contact resistance might lead to further improvements. Due to the homogenous structure in the radial direction, shear stresses are minimized and large winding heights can be realized in principle. The DUDA concept of coil windings can be used to build even more sophisticated magnetic arrangements, e.g. Halbach-arrays, or complex windings for new stator configurations of rotating machines. The optional miniaturization offers compact and powerful magnets, e.g. for accelerators too.

Preliminary design optimization of a fully superconducting motor based on disk-up-down-assembly magnets

“…The maximum z-component of the magnetic field generated by the Halbach arrays is 1.11 T. This is limited by the current-carrying ability of the tapes used. If the critical current density of the superconducting tapes is increased to I c = 725 A mm −2 at 30 K, 3 T, as presented in [24], the Halbach array can generate a magnetic field of 2.65 T at 2 mm from the upper surface of the magnets. These field values are suitable for the air-gap magnetic field in electric motors.…”

“…In order to take advantages of the aforementioned three types of superconducting magnets, a new concept, named as disk-up-down-assembly ('DUDA'), was developed from the widely used copper Bitter magnets in high field areas and was initially proposed by Arndt from Karlsruhe Institute of Technology, as shown in figure 2 [24]. Short superconducting tapes are first cut or manufactured in a rectangular or circular shape with a slit.…”

A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

“…However, resistive Bitter magnets impose prodigious demands for electrical power and cooling (32 MW of electrical power and 270 l s −1 of de-ionised water cooling for a 41.5 T magnet [3]) which largely preclude their application outside dedicated facilities. Recently, there have been efforts to overcome these limitations by recreating the Bitter winding geometry using high-temperature superconducting (HTS) coated-conductors (CCs) [4][5][6][7]. To date, proofof-concept experiments have generated a maximum steadyoperation central field of ≈65 mT in a 42 turn stack carrying 17.8 A [4].…”

“…Recently, there have been efforts to overcome these limitations by recreating the Bitter winding geometry using high-temperature superconducting (HTS) coated-conductors (CCs) [4][5][6][7]. To date, proofof-concept experiments have generated a maximum steadyoperation central field of ≈65 mT in a 42 turn stack carrying 17.8 A [4]. Other authors have also reported 'Bitter-like' HTS CC magnets [8][9][10], however in those cases this is a misnomer, as the reported devices do not realise a helical current path within the coil.…”