A Model for Magnetic Instabilities in Hard Superconductors: The Adiabatic Critical State
A Model for Magnetic Instabilities in Hard Superconductors: The Adiabatic Critical State
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DOI：
10.1063/1.1655898
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发表时间：
1968-10
影响因子：
3.2
通讯作者：
P. Swartz;C. P. Bean
中科院分区：
文献类型：
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作者：
P. Swartz;C. P. Bean
推广了硬质超导体的等温临界态模型，考虑了外加磁场突然变化和磁通绝热进入块体时的加热效应。我们考虑以下具体情况。一块半无限大的超导体在其表面的磁场中冷却。接下来，将外场等温地升高一个量HS。这个超额场从表面线性减小到深度δ=10Hs/4πJc。最后，在比热扩散时间短而比电磁扩散时间长的时间内，场被提高了无穷小的ΔH。暴露在变化场中的每个体积元素接收与局部磁通变化时间Jc成比例的热脉冲。这种热脉冲反过来降低了临界电流，使更多的磁通得以穿透。我们发现，如果HS超过某一临界值HfJ，那么等温临界态并不是超导体的唯一允许态。
The isothermal critical‐state model of hard superconductors is extended to include the effects of heating when the applied field is changed suddenly and magnetic flux enters adiabatically into the bulk. We consider the following specific situation. A semi‐infinite slab of superconductor is cooled in a magnetic field lying in its surface plane. Next, the external field is raised isothermally by an amount Hs. This excess field decreases linearly to a depth δ= 10Hs/4πJc from the surface. Finally, the field is raised by an infinitesimal amount ΔH in a time short compared to the thermal diffusion time and long compared to the electromagnetic diffusion time. Each element of volume exposed to the changing field receives a thermal impulse proportional to the local‐flux‐change times Jc. This thermal impulse, in turn, lowers the critical current and allows more flux to penetrate. We find that if Hs exceeds some critical value Hfj, then the isothermal critical state is not the only allowed state of the superconducto...