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首页> 外文期刊>Physica, C. Superconductivity and its applications >Pulsed eddy current transient technique with HTS SQUID magnetometer for non-destructive evaluation
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Pulsed eddy current transient technique with HTS SQUID magnetometer for non-destructive evaluation

机译：采用HTS SQUID磁力计的脉冲涡流瞬变技术进行无损评估

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Eddy current non-destructive evaluation (NDE) often uses excitation currents at a fixed frequency, which determines the depth of investigation due to the skin effect. We developed a novel pulsed eddy current NDE technique which potentially may cover a broader depth range, by analyzing the decay of the recorded transient. Eddy currents in the inspected aluminium structures were induced by turn-off of the primary magnetic field pulse in a transmitter coil. The secondary magnetic field created by the induced currents was recorded by an HTS superconducting quantum interference device magnetometer. The quickly decaying early time data of the transient signal corresponds to the information from upper layers of the plate, while the late time data delivers information from deep layers. In order to suppress environmental noise and increase the signal-to-noise ratio, repetitive square-wave pulses were used. The transient response of the plate was recorded in off-time between the transmitter pulses and averaged using a commercial LAPTEM data acquisition unit. Measurements of a crack at different depths in a stacked aluminium sample are presented. The data was analyzed by calculating the apparent conductivity of the sample as a function of depth, a technique often used in Geophysical data interpretation. Possible advantages and drawbacks of this new transient NDE technique are discussed. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 5]
机译：涡流无损评估（NDE）通常使用固定频率的励磁电流，由于集肤效应，这决定了研究的深度。通过分析记录瞬态的衰减，我们开发了一种新颖的脉冲涡流NDE技术，该技术可能覆盖更广的深度范围。被检铝结构中的涡流是由发射器线圈中的初级磁场脉冲关闭引起的。由感应电流产生的次级磁场由HTS超导量子干涉仪磁力计记录。瞬态信号的快速衰减的早期数据对应于来自板高层的信息，而晚期数据则传递来自较深层的信息。为了抑制环境噪声并提高信噪比，使用了重复的方波脉冲。在发射器脉冲之间的关闭时间内记录板的瞬态响应，并使用商用LAPTEM数据采集单元进行平均。提出了在堆叠的铝样品中不同深度处的裂纹的测量值。通过计算样品的表观电导率作为深度的函数来分析数据，这是地球物理数据解释中经常使用的一种技术。讨论了这种新的瞬态NDE技术的可能的优缺点。 （C）2002 Elsevier Science B.V.保留所有权利。 [参考：5]

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