中国物理B ›› 2025, Vol. 34 ›› Issue (7): 77402-077402.doi: 10.1088/1674-1056/adcdec
Fabrication and characterization of MgB2 spherical shells with reduced thickness on 1 mm diameter Si3N4 spheres
Ruining Sun(孙瑞宁)1, Tiequan Xu(徐铁权)1,2, Yue Wang(王越)1,†, Furen Wang(王福仁)1, and Zizhao Gan(甘子钊)1
- 1 Applied Superconductivity Center, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China;
2 Beijing National Laboratory for Molecular Sciences, Huairou Research Center, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
Fabrication and characterization of MgB2 spherical shells with reduced thickness on 1 mm diameter Si3N4 spheres
Ruining Sun(孙瑞宁)1, Tiequan Xu(徐铁权)1,2, Yue Wang(王越)1,†, Furen Wang(王福仁)1, and Zizhao Gan(甘子钊)1
- 1 Applied Superconductivity Center, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China;
2 Beijing National Laboratory for Molecular Sciences, Huairou Research Center, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
摘要： Magnetic levitation of the fusion target by coating a thin MgB$_2$ superconducting shell on its outer surface has recently been proposed in inertial confinement fusion (ICF) to realize a noncontact support of the target at $\sim20$ K to boost the implosion performance and fusion yield. To avoid possible effects on target ablation, the coated MgB$_2$ shell is anticipated to be as thin as possible while fulfilling the target levitation requirements. Under this circumstance, the fabrication of an MgB$_2$ shell with reduced thickness has been explored using a hybrid physical-chemical vapour deposition method. By gradually decreasing the deposition time, a set of MgB$_2$ shells were grown on 1 mm diameter Si$_3$N$_4$ spheres with the thickness reducing from 720 nm to 200 nm. The spherical shells all have a polycrystalline structure characterized by closely packed hexagonal grains, with both the grain size and thickness diminishing as the shell thickness decreases. The superconducting transition temperature $T_{\rm c}$ of the shells, as determined by both resistance and magnetization measurements, is in the range of $38$-$40$ K and all shells exhibit ideal diamagnetism at low temperatures. For the thinnest shell of 200 nm, the superconducting critical current density $J_{\rm c}$ at 20 K reaches $8.0\times10^6$ A/cm$^2$ and $2.1\times10^5$ A/cm$^2$ under zero and 2 T applied field, respectively. The results indicate that it is experimentally feasible to fabricate MgB$_2$ spherical shells with a thickness as low as 200 nm while maintaining the high $T_{\rm c}$ and $J_{\rm c}$, thereby taking a further step towards the application of the shell in superconducting magnetic levitation for ICF.
中图分类号: (Superconducting films and low-dimensional structures)
- 74.78.-w