Campbell法研究MgB_2临界电流密度

Study on the MgB_2 critical current density with campbell method

PIT(powder in tube)法制备了MgB2超导材料;用Campbell法测量了样品的外加交流磁场bac与磁通渗透深度λ′的关系,并计算得到样品在外磁场中的临界电流密度;讨论了bac-λ′,曲线误差形成的原因和选取曲线平稳部分为计算有效段原则;Campbell法测量考虑了样品的整体结构影响电流的特性,得到的结果更切合超导材料的实际临界电流密度。

MgB2 superconducting materials were prepared with PIT（powder in tube）method.The magnetic flux penetration depth（λ′）of the MgB2samples were measured in Campbell method at the different additional alternating magnetic flux density（bac）,and the critical current density in different magnetic fields were calculated. The error causations of the bacvsλ′curves and the principle that the smooth parts in the curve are selected as availabe segments to calculate were briefly discussed.Characteristics that the integral microstructure of the sample influences the current is taken into consideration in this measure method,the critical current density obtained in this way is more correspond with reality.