Research on high-Tc SQUID based non-destructive evaluation

• 来源期刊: 中国物理（英文版）
• 关键词: SQUID resolution eddy current
• 年，卷（期）: 2004,（1）
• 页码范围: 19-23
• 页数: 5页
• 语种: 英文

摘要

A non-destructive evaluation system based on high-Tc dc-SQUID (superconducting quantum interference device)incorporating a gradient field excitation has been built. By using this system a 1mm-diameter hole at a depth of 2mm inside an aluminium plate at room temperature can be easily detected and imaged in an unshielded environment. The relation between the spatial resolution, or the smallest detectable flaw size, and experimental parameters is briefly analysed in terms of a simple metal ring model. The result shows that the spatial resolution depends strongly on the sensor-sample separation as well as on some other parameters, such as signal-to-noise ratio of excitation, excitation frequency and material conductivity.