Abstract
Attainable critical current characteristics in the future are theoretically investigated based on the flux pinning mechanism of grain boundaries for superconducting MgB2 wires and thin films in the dirty limit. A relatively high volume fraction by diffusion processes and high upper critical field by C-addition are assumed for the wire. The critical current density in a normal magnetic field is calculated for a c-axis aligned thin film with full connectivity. The flux creep-flow model is used for both cases to estimate the critical current density. It is found the critical current density of the thin film is very high at low temperatures and low magnetic fields due to higher electrical connectivity, although it is significantly degraded at high temperatures and high magnetic fields due to flux creep. However, it is expected that these wires and thin films can carry critical currents of very high density in a magnetic field up to 10 T at 15 K. This shows that MgB2 is a promising superconductor that can be applied for equipment operating at medium temperatures.
