Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method
Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method
复制标题
DOI：
10.3389/feart.2015.00005
复制
发表时间：
2015-01-01
影响因子：
2.9
通讯作者：
Kodama, Kazuto
中科院分区：
文献类型：
--
作者：
Kodama, Kazuto
提出了一种利用脉冲磁化仪测量天然样品在11 ms脉冲磁场作用下的瞬态磁化强度的新方法。构建了一个实验系统，该系统由一对差分传感线圈与高速数字示波器相连进行数据采集。将数据输入计算机，得到了在快速变化的正磁场中的初始磁化曲线和磁滞回线的下降分支。该系统进行了测试与合成样品（坡莫合金带，铝板，镍粉）以及两个火山岩样品。从合成样品的结果显示出相当大的差异，通过准静态方法使用振动样品磁强计（VSM）测量。这些差异主要是由于随时间变化的磁性或电磁效应，如磁粘度，涡流损耗，或磁弛豫。天然样品的结果表明，瞬态磁化场曲线在很大程度上与磁滞回线的相应部分相当。然而，在脉冲结束时的相对磁化强度（按比例缩放到饱和磁化强度）大于VSM测量的相对磁化强度。这种差异，以及脉冲后快速指数衰减的发生，表明磁驰豫可以用畴壁位移来解释。这些结果表明，随着进一步的发展，所提出的技术可以成为一个有用的工具，用于表征包含在各种天然材料中的磁性颗粒。
This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples(permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that, with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.