Non-destructive flaw detection and profiling in paramagnetic materials using QWHE sensors

该项目旨在开发使用先进的量子井霍尔效应(QWHE)传感器的电磁无损检测(NDT)的新方法。该博士的重点是开发使用多频场应用的顺磁材料成像系统，允许对样品进行多层成像。在本博士课程中发展的基础知识将适用于实际的工业应用，如石油和天然气管道监测和航空航天生产。该项目目前包括开发高频(&gt；100 kHz)和低频(&lt；1 kHz)的手持涡流检测(ECT)系统，以及用于多频扫描组合的图像处理技术。随着该项目的继续，还将开发多频率现场应用技术。这将通过电磁建模、电路设计、电磁仿形和信号/图像处理过程来实现。这些一般步骤适用于在本博士课程中开发的任何系统。随着系统的发展，PHD还将包括数据收集，以表征顺磁金属成像的最佳参数。虽然标准的ECT系统在工业上使用，但它们都主要使用基于线圈的检测，限制了它们的传感器的物理尺寸限制。由于线圈对磁场的非线性响应，基于线圈的ECT系统产生的图像往往难以解释。相比之下，QWHE传感器的高线性度、宽动态范围和灵敏度使其成为高分辨率磁成像的最佳选择，并且在高频(&gt；100 kHz)时，有机会将实际线圈本身集成到半导体管芯中，从而实现极其紧凑的照明传感器探头(&lt；0.5x0.5 mm2)。传感器的频率线性响应也为在非常低的频率下进行ECT提供了可能性，允许使用当前方法无法扫描的磁穿透深度。最后，当线圈检测限制在其区域内的磁通量时，其灵敏度受到尺寸的限制。相比之下，QWHE检测磁通密度，因此，它们被限制在3x2 mm的封装中，实际感测区域的大小约为20x20到5x5微米。这为创建QWHE阵列提供了可能性，可能导致实时电磁无损检测。这一创新之处在于发现和监控目前通过无损检测方法看不到的缺陷和缺陷的潜力，使人们能够更深入地了解工业使用中的金属是如何在其使用寿命内产生缺陷的。

This project aims to develop new methods of electromagnetic Non-Destructive Testing (NDT) using advanced Quantum Well Hall Effect (QWHE) sensors. The focus of this PhD is on developing systems for the imaging of paramagnetic materials using multifrequency field applications, allowing multilayer images of the samples. The underpinning knowledge developed over the course of this PhD will be applicable to real industrial applications such as oil and gas pipe monitoring, and aerospace production.The project currently consists of development of handheld systems for Eddy Current Testing (ECT), both at high frequencies (>100kHz) and low frequencies (<1kHz), along with image processing techniques for multifrequency scan combination. As the project continues, multifrequency field application techniques will also be developed. This will be achieved through a process of electromagnetic modelling, circuit design, electromagnet profiling, and signal/image processing. These general steps apply to any systems to be developed over the course of this PhD. As systems are developed the PhD will also include collection of data in order to characterise the optimal parameters for paramagnetic metal imaging.While standard ECT systems are used in industry, they all use mostly coil based detection, limiting them to the physical size restrictions of their sensors. As coils have a non-linear response to magnetic field, the images produced by coil based ECT systems are often difficult to interpret. In contrast, the high linearity, wide dynamic range, and sensitivity of the QWHE sensors leads them to be excellent for high resolution magnetic imaging and at high frequencies ( > 100kHz) there is the opportunity to integrate the actual coils itself within the semiconductor die leading to extremely compact illumination-sensor probes ( < 0.5x0.5 mm2). The frequency linear response of the sensors also opens the possibility for ECT performed at very low frequencies, allowing for magnetic penetration depths not possible to scan with current methods. Finally, while coils detect magnetic flux confined within their area, their sensitivity is limited by size. In contrast, QWHEs detect magnetic flux density, and as such, they are confined to 3x2mm packages, with the actual sensing area is around 20x20 to 5x5microns in size. This opens possibilities for creating QWHE arrays, potentially leading to real time electromagnetic NDT.The novelty of this is in the potentials for discovering and monitoring flaws and defects that are currently not visible through NDT methods, allowing for a deeper understanding of how metals in industrial use develop flaws over their lifetimes.