一种具有聚焦作用的线圈涡流问题解析解

Analytical Solution of Eddy Current Problem Due to a Figure-8-shaped Coil Above a Conducting Plate

为检测导体内更深处的缺陷,提出用8字形线圈作为涡流检测线圈,得到了8字形线圈在半无限大线性导体上方时涡流问题的解析解。仿真计算表明,与平行于导体表面放置的圆环形线圈相比,8字形线圈所激励的涡流密度峰值更大,能量分布更集中。试验验证了斜置线圈的阻抗表达式。研究结果可用于指导涡流检测探头的设计。

The eddy current problems of a figure-8-shaped coil were studied with analytical method. The study was based on the theory of eddy current field due to a circular current loop in an arbitrary position above a conducting plate . Expression of impedance increment of the figure-8-shaped coil, as well as the eddy current distribution within conducting medium, versus the angle between the double loops of figure-8-shaped coil was presented. By the means of simulation, it was concluded that eddy current density in conducting plate excited by the figure-8-shaped coil was greater and its distribution was more concentrative compared with that by a current loop parallel to plate in the same conditions. The result could be applied in eddy current testing sensor design.