The development of superconducting joining technology for reacted magnesium diboride(MgB_(2))conductors remains a critical challenge for the advancement of cryogen-free MgB_(2)-based magnets for magnetic resonance ima...The development of superconducting joining technology for reacted magnesium diboride(MgB_(2))conductors remains a critical challenge for the advancement of cryogen-free MgB_(2)-based magnets for magnetic resonance imaging(MRI).Herein,the fabrication of superconducting joints using reacted carbon-doped multifilament MgB_(2)wires for MRI magnets is reported.To achieve successful superconducting joints,the powder-in-mold method was employed,which involved tuning the filament protection mechanism,the powder compaction pressure,and the heat treatment condition.The fabricated joints demonstrated clear superconducting-to-normal transitions in self-field,with effective magnetic field screening up to 0.5 T at 20 K.To evaluate the interface between one of the MgB_(2)filaments and the MgB_(2)bulk within the joint,serial sectioning was conducted for the first time in this type of superconducting joint.The serial sectioning revealed space formation at the interface,potentially caused by the volume shrinkage associated with the MgB_(2)formation or the combined effect of the volume shrinkage and the different thermal expansion coefficients of the MgB_(2)bulk,the filament,the mold,and the sealing material.These findings are expected to be pivotal in developing MgB_(2)superconducting joining technology for MRI magnet applications through interface engineering.展开更多
Magnesium diboride(MgB_(2))magnets have the potential to be the next-generation liquid-helium-free magnet for magnetic resonance imaging(MRI)application due to their relatively high superconducting transition temperat...Magnesium diboride(MgB_(2))magnets have the potential to be the next-generation liquid-helium-free magnet for magnetic resonance imaging(MRI)application due to their relatively high superconducting transition temperature,high current density and low raw material cost compared with current commercial niobium-titanium(Nb-Ti)magnets.A typical superconducting magnet includes several coils.To produce an ultra-stable magnetic field for imaging in MRI,a superconducting electromagnet operating in a persistent mode is crucial.Superconducting coils of the electromagnet in MRI are short-circuited to operate in the persistent mode by connecting coils with superconducting joints.Per-sistent joints have been demonstrated for in-situ and ex-situ wires of both mono-and multi-filamentary structures,made predominantly by PIT techniques similar to those used in wire production.To realise further engagement of MgB_(2)in MRI applications,enhancing the performance of MgB_(2)superconducting joints is essential.This literature review summarises research and development on MgB_(2)superconducting joining technology.展开更多
基金the Japan Society for the Promotion of Science(JSPS)KAKENHI Grant Number JP18F18714Cryogenic Station,Research Network and Facility Services Division,National Institute for Materials Science(NIMS),Japansupported by the ARC Linkage Project(LP200200689)。
文摘The development of superconducting joining technology for reacted magnesium diboride(MgB_(2))conductors remains a critical challenge for the advancement of cryogen-free MgB_(2)-based magnets for magnetic resonance imaging(MRI).Herein,the fabrication of superconducting joints using reacted carbon-doped multifilament MgB_(2)wires for MRI magnets is reported.To achieve successful superconducting joints,the powder-in-mold method was employed,which involved tuning the filament protection mechanism,the powder compaction pressure,and the heat treatment condition.The fabricated joints demonstrated clear superconducting-to-normal transitions in self-field,with effective magnetic field screening up to 0.5 T at 20 K.To evaluate the interface between one of the MgB_(2)filaments and the MgB_(2)bulk within the joint,serial sectioning was conducted for the first time in this type of superconducting joint.The serial sectioning revealed space formation at the interface,potentially caused by the volume shrinkage associated with the MgB_(2)formation or the combined effect of the volume shrinkage and the different thermal expansion coefficients of the MgB_(2)bulk,the filament,the mold,and the sealing material.These findings are expected to be pivotal in developing MgB_(2)superconducting joining technology for MRI magnet applications through interface engineering.
基金thankful for the support from the Australian Research Council(ARC)Linkage Project(LP200200689).
文摘Magnesium diboride(MgB_(2))magnets have the potential to be the next-generation liquid-helium-free magnet for magnetic resonance imaging(MRI)application due to their relatively high superconducting transition temperature,high current density and low raw material cost compared with current commercial niobium-titanium(Nb-Ti)magnets.A typical superconducting magnet includes several coils.To produce an ultra-stable magnetic field for imaging in MRI,a superconducting electromagnet operating in a persistent mode is crucial.Superconducting coils of the electromagnet in MRI are short-circuited to operate in the persistent mode by connecting coils with superconducting joints.Per-sistent joints have been demonstrated for in-situ and ex-situ wires of both mono-and multi-filamentary structures,made predominantly by PIT techniques similar to those used in wire production.To realise further engagement of MgB_(2)in MRI applications,enhancing the performance of MgB_(2)superconducting joints is essential.This literature review summarises research and development on MgB_(2)superconducting joining technology.