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

本项目旨在利用先进的量子阱霍尔效应（QWHE）传感器开发电磁无损检测（NDT）的新方法。本博士的重点是利用多频场应用开发顺磁性材料成像系统，允许样品的多层图像。在本博士课程中发展的基础知识将适用于实际工业应用，如石油和天然气管道监测，以及航空航天生产。该项目目前包括开发用于涡流测试（ECT）的手持式系统，包括高频（100kHz）和低频（<1kHz），以及用于多频扫描组合的图像处理技术。随着项目的继续，还将开发多频现场应用技术。这将通过电磁建模、电路设计、电磁体分析和信号/图像处理的过程来实现。这些一般步骤适用于本博士课程中要开发的任何系统。随着系统的发展，博士学位也将包括收集数据，以表征顺磁金属成像的最佳参数。虽然标准的ECT系统在工业中使用，但它们大多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。由于线圈对磁场具有非线性响应，基于线圈的ECT系统产生的图像通常难以解释。相比之下，QWHE传感器的高线性度，宽动态范围和灵敏度使它们非常适合高分辨率磁成像，并且在高频率（> 100kHz）下，有机会将实际线圈本身集成在半导体芯片内，从而实现极其紧凑的照明传感器探头（< 0.5x0.5 mm2）。传感器的频率线性响应也开启了在极低频率下进行ECT的可能性，允许用当前方法无法扫描的磁穿透深度。最后，当线圈检测局限在其区域内的磁通量时，它们的灵敏度受到尺寸的限制。相比之下，QWHEs检测磁通量密度，因此，它们被限制在3x2mm的封装中，实际传感面积约为20x20至5x5微米。这为创建QWHE阵列提供了可能性，有可能实现实时电磁无损检测。这种方法的新颖之处在于发现和监测目前通过无损检测方法无法看到的缺陷和缺陷的潜力，从而可以更深入地了解工业用金属在其使用寿命期间如何产生缺陷。

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.