Thin Alternatives to Braided Glass Insulation for Low-Temperature Superconducting Wire

60370 Internal tin Nb3Sn superconducting strands and Rutherford cables are the focus of superconducting magnet fabrications for high field physics applications. During magnet processing and operation, the strands and cables are subjected to large stresses and it is essential that these cables and their insulation perform under these conditions. In addition, the insulation for the superconducting wires and cables should be capable of withstanding temperatures over 600-800¿C, the reaction temperature of Nb and Sn filaments when forming superconductor. This project seeks to produce high dielectric strength, high modulus, and ultra-thin ceramic insulator for internal tin Nb3Sn superconducting strands and Rutherford cables. The insulation would not only substantially improve magnet performance, eliminating complex coil fabrication steps and lowering production cost, but also enable new designs that would allow superconducting magnets to achieve maximum field strength and system lifetime. In Phase I, a patented Combustion Chemical Vapor Deposition (CCVD) technique was used to deposit silica, boron-doped silica, and silica/alumina coatings onto unreacted, internal tin Nb3Sn wire as electrical insulation. These coatings were found to insulate over 200 V under face-to-face contact breakdown voltage tests. In Phase II, experiments will focus on optimizing the CCVD process parameters to deposit insulating coatings onto the internal tin multifilament single strands and Rutherford cables. Mechanical properties of the coatings and the resultant coated wires will be investigated. The reel-to-reel system will be fully automated and capable of coating practical lengths of wire for magnet fabrication. Commercial Applications and Other Benefits as described by the awaredee: The use CCVD to deposit thin, high modulus, high dielectric strength, and thermal¿mechanically compatible insulation to internal tin Nb3Sn superconducting strands and Rutherford cables should enable novel designs in superconducting magnet for the application of high field physics. The CCVD process also could be used to produce multi-component ceramics because of its flexibly in doping and composing elements in the coating. The CCVD process can be used to manufacture long-length wire because of its scalability.