Second Generation Wire Development at AMSC

The Second Generation (2G) High Temperature Superconducting (HTS) wire is being used in a range of applications including cables, FCL’s, rotating machines and high field magnets. The basic wire used in all these applications is based on a composite architecture consisting of a thin YBCO superconducting layer deposited on one side of a thin, flexible metal substrate. The HTS/substrate composite is typically surrounded by an electrochemically deposited Cu layer or laminated between two thin metal strips. This basic composite architecture has been virtually unchanged since the initial development of the 2G HTS wire technology. AMSC has been examining alternate composite architectures which incorporate two HTS layers bonded to each side of a thin metal foil. This double HTS layer composite can be surrounded by an electroplated Cu layer or laminated between two metal strips, resulting in a wire package nearly indistinguishable from the today’s typical HTS wire, but with up to twice the critical current.<br/>Pinning enhancement in today’s state-of-the-art 2G HTS wire is typically achieved through the incorporation of rare earth nanoparticles or columnar structures based on materials such as BaZrO₄. Although both approaches are successful in enhancing the pinning over a range of temperatures and magnetic fields, slight variations on the chemical composition or structure can result in variations in the pinning enhancement between wires or even along the length of a wire. AMSC has been examining an alternate approach which significantly enhances pinning and is highly reproducible. The approach is based on the introduction of a uniform defect structure generated during a reel-to-reel ion irradiation of a fully processed YBCO layer by ions such as Au⁵⁺. By controlling the irradiation parameters, the pinning enhancement can be tuned for specific temperatures and magnetic fields.<br/>In this presentation, we will update progress on the development of the novel wire architectures and pinning enhancements under development at AMSC.<br/>This work is supported by EERE under contract DE-EE0007870.