Advances in MgB$_2$ Superconductor Applications for Particle Accelerators

The MgB$_2$ superconductor, discovered in 2001, has provided unique compound features of magnesium diboride with much higher critical temperature and critical field compared to NbTi superconductor. Its applications have been expanding owing to its superior energy balance in high-temperature operation and to its excellent stability and operational margin because of the higher critical temperature and heat capacity. This paper reviews the recent advances in MgB$_2$ applications in the field of particle accelerators focusing on superconducting power transmission (superconducting link) and superconducting magnets, and also briefly discusses the future prospects and improvement expected such as radiation hardness issues and cost-effective fabrication for wider applications and industrialization.