Electromagnetic nondestructive evaluation: moving HTS SQUIDs, inducing field nulling and dual frequency measurements
Electromagnetic nondestructive evaluation: moving HTS SQUIDs, inducing field nulling and dual frequency measurements
复制标题
电磁无损评估：移动 HTS SQUID、感应场归零和双频测量
DOI：
10.1109/77.622051
复制
发表时间：
1997
影响因子：
1.8
通讯作者：
A. Cochran
中科院分区：
文献类型：
--
作者：
C. Carr;D. McKirdy;E. Romans;G. Donaldson;A. Cochran
我们之前已经证明，简单的单层高温超导SQUID可以有效地用于在磁性非屏蔽环境中使用涡流技术进行电磁无损评估(NDE)。用于无损检测应用的高温超导SQUID系统预计将是小巧和便携的，允许在静止样品上方的地球磁场中进行非静止测量。在这里，我们展示了面向应用的结果，展示了我们的HTS电子梯度仪处理飞机级铝样品中一系列模拟缺陷上的传感器移动的能力。为了能够探测精细的表面和亚表层结构，我们对两个SQUID应用了有源场零化，以提高有效信噪比。激励信号通过非超导线圈施加，为每个设备提供较低的磁场环境。我们还介绍了使用双频涡流技术对多层结构中的缺陷进行深度剖析的结果。
We have previously shown that simple, single layer HTS SQUIDs can be used effectively in electromagnetic nondestructive evaluation (NDE) using eddy current techniques in a magnetically unshielded environment. HTS SQUID systems for NDE applications are expected to be small and portable allowing non-stationary measurements to be carried out in the Earth's field above a stationary sample. Here we present application-oriented results showing the ability of our HTS electronic gradiometer to cope with the movement of the sensors above a series of simulated flaws in aircraft grade aluminum samples. To permit the detection of fine surface and subsurface structures we have applied active field nulling to the two SQUIDs to increase the effective signal to noise ratio. The excitation signal is applied via a non-superconducting coil to provide a lower field environment for each device. We also present results using a dual frequency eddy current technique to allow depth profiling of flaws in multilayer structures.