Chabanenko Viktor, Nabiałek Adam, Puźniak Roman
O. Galkin Donetsk Institute for Physics and Engineering, National Academy of Science, Pr. Nauki 46, 03028 Kyiv, Ukraine.
Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, PL-02668 Warsaw, Poland.
Materials (Basel). 2022 Mar 10;15(6):2037. doi: 10.3390/ma15062037.
Avalanche cascades of magnetic flux have been detected at thermomagnetic instability of the critical state in the plates of Nb-Ti alloy. It was found that, the magnetic flux Φ enters conventional superconductor in screening regime and leaves in trapping regime in the form of a multistage "stairways", with the structure dependent on the magnetic field strength and magnetic history, with approximately equal successive portions ΔΦ in temporal Φ() dependence, and with the width depending almost linearly on the plate thickness. The steady generation of cascades was observed for the full remagnetization cycle in the field of 2-4 T. The structure of inductive signal becomes complex already in the field of 0-2 T and it was shown, on the base of Fourier analysis, that, the avalanche flux dynamic produces, in this field range, multiple harmonics of the electric field. The physical reason of complex spectrum of the low-field avalanche dynamics can be associated with rough structure of moving flux front and with inhomogeneous relief of induction. It was established that the initiation of cascades occurs mainly in the central part of the lateral surface. The mechanism of cascades generation seems to be connected to the "resonator's properties" of the plates.
在Nb-Ti合金板临界状态的热磁不稳定性中检测到了磁通量的雪崩级联。研究发现，磁通量Φ在屏蔽状态下进入常规超导体，并以多级“阶梯”的形式在俘获状态下离开，其结构取决于磁场强度和磁历史，在时间Φ(t)依赖关系中连续部分ΔΦ近似相等，宽度几乎与板厚度呈线性关系。在2-4T的磁场中，观察到了全再磁化循环中雪崩级联的稳定产生。感应信号的结构在0-2T的磁场中就已经变得复杂，基于傅里叶分析表明，在该磁场范围内，雪崩通量动态产生电场的多个谐波。低场雪崩动力学复杂频谱的物理原因可能与移动通量前沿的粗糙结构和感应不均匀有关。已确定级联的起始主要发生在侧面的中心部分。级联产生的机制似乎与板的“谐振器特性”有关。
