Research and development of MgB2 materials for practical applications

Since the discovery of the superconductivity of MgB2 in 2001, extensive efforts at fundamental and/or engineering studies on MgB2 have been made worldwide. Superconducting properties, such as upper critical field and critical current density, have been improved. Currently, long MgB2 wires exceeding 1 km length can be manufactured, and the development of various application systems using MgB2 wires is ongoing. For example, a magnetic resonance imaging (MRI) system using MgB2 magnets was constructed and images of human brain were successfully acquired in late 2006. In this review, an overview of the research on MgB2 wires from both materials science and application development aspects is presented. (author)