A theoretical model of Lorentz force particle analyzer: a potential flow perspective

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Copper and aluminum foils serve as predominant materials in fluid collectors, and defects within them can significantly impact the electrochemical performance of cells. However, existing methods for detecting defects within non-ferromagnetic thin metals, such as copper and aluminum foils, have several limitations. This study aims to address the need for detecting micrometer-scale defects on 0.1 mm copper foils, aligning with industrial field requirements. We devised an inspection device based on the induced magnetic field detection principle and explored the impact of copper foil undulations on micrometer-scale defect detection using COMSOL modeling. Subsequently, we introduced a coherent cumulative-differential algorithm to effectively mitigate the influences of circuit noise and sampling heave noise on defect signals. Consequently, the signal-to-noise ratios of 100- and 200-micron defect signals were significantly improved by 157% and 234%, respectively. This approach shows promise for detecting micrometer-scale defects in non-ferromagnetic thin metals and lays a robust foundation for future defect identification and inversion endeavors.

Section: Basic Principlementioning

confidence: 99%

Non-ferromagnetic thin metal micron-sized defect detection system based on a coherent accumulation-difference method

Wei,

Chen,

Liu

et al. 2024

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“…At present, LFPA technique has been analyzed in theory and in numerical simulation respectively [18][19][20][21][22][23], and furthermore, relevant prototype experiments also have been carried out [17,24,25]. In the liquid prototype experiment, water and GaInSn alloy were driven by two syringe pumps severally, to simulate the flowing liquid metal and inclusion particles.…”

Section: Introductionmentioning

confidence: 99%

Prototype of low melt-point liquid metal performance of Lorentz force particle analyzer

Zhang¹,

Wang²,

Liu³

et al. 2021

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Lorentz force particle analyzer (LFPA) is a non-contact electromagnetic measurement technique for the cleanliness inspection of liquid metal. Based on its principle, an optimized prototype of micro-particle measurement device is designed and built. Inclusion particles of different sizes in millimeter and submillimeter in liquid metal are inspected by this device at room temperature. The characteristics and formation mechanisms of typical inclusion particles pulse signal and laser path signal are compared and discussed. The wavelet decomposition method is used to denoise the original signal, and the desired signal is extracted and sorted out. Results show that LFPA is suitable for the measurement of inclusion particles in liquid metal.

“…Recently, another innovative and simple method termed the Lorentz force particle analyzer (LFPA) [10][11][12][13] has been proposed, its basic principle will be described in the next section and this method is inspired by another existing technique named Lorentz force velocimetry (LFV) [14][15][16]. The LFPA can be applied to overcome the challenges described above for the LiMCA because it is a contactless method for particle inspection via magnetic induction.…”

Section: Introductionmentioning

confidence: 99%

Numerical calibration of a Lorentz force particle analyzer

Wang¹,

Wang²

2018

A Lorentz force particle analyzer (LFPA) is a device for the contactless measurement of micron-sized particles in an electrical conductor. Calibration is vital for the successful application of an LFPA. In this article, we first show that the presence of particles that possess the same size but are located at different positions will lead to variations of their measured quantity; therefore, the LFPA requires calibration. Then, two numerical models are developed to solve this problem. For the case of a wire, a Halbach-array magnetic system with 24 segments replaces the cubic permanent magnet (PM) to generate a homogeneous magnetic field in the working area. Three identical sensors are arranged around the wire at azimuthal intervals of 2π/3 and at certain distances (double the size of the magnetic system) in the axial direction, and the resultant values of the calibration deviation coefficient (η) smaller than 6% except for the case of edge. For the case of a thin sheet, we create an arc-like boundary at the front of the cubic PM to reduce the gradient of the magnetic flux density along the through-thickness direction. Two sensors are placed at the two sides of the thin sheet, and η ⩽ 10% is obtained. These results imply that the numerical models presented here are simple, robust and reliable methods for the numerical calibration of an LFPA and may become a low-cost alternative to the expensive full-scale calibration achieved by the experiment.