Ural Federal University, Institute of Natural Sciences and Mathematics, 19 Mira Street, 620002 Ekaterinburg, Russia.
Rev Sci Instrum. 2023 Mar 1;94(3):034702. doi: 10.1063/5.0131896.
The article presents a Hall effect magnetometer for use in a desktop Electron Paramagnetic Resonance spectrometer with a permanent magnet system and scanning coils. High accuracy and long-term stability at a small size and low cost are achieved through the use of digital signal processing, sequential data filtering in the time and frequency domains, as well as digital correction of raw data based on calibration information. The exciting current of the Hall sensor has the form of an alternating-sign square wave formed by a high-speed H-bridge powered by a stable direct current. Generation of control signals, time selection of data, and their accumulation are performed using Xilinx Field-Programmable Gate Array Artix-7. MicroBlaze embedded 32-bit processor is used to control the magnetometer and interface with adjacent levels of the control system. Taking into account the individual characteristics of the sensor, including the offset voltage, the nonlinearity of the magnetic sensitivity, and their temperature dependences, is carried out by correcting the data obtained by calculating a polynomial depending on the raw magnitude of the field induction and the temperature of the sensor. The polynomial coefficients are individual for each sensor, are determined once during the calibration process, and are stored in the dedicated Electrically Erasable Programmable Read-Only Memory. The magnetometer has a high resolution of 0.1 µT and an absolute measurement error of not exceeding 6 µT.
本文介绍了一种用于台式电子顺磁共振波谱仪的霍尔效应磁强计，该仪器采用永磁体系统和扫描线圈。通过数字信号处理、时域和频域的顺序数据滤波以及基于校准信息对原始数据进行数字校正，实现了小尺寸、低成本、高精度和长期稳定性。霍尔传感器的激励电流采用由稳定直流供电的高速 H 桥形成的交变符号方波形式。控制信号的产生、数据的时间选择及其累积使用 Xilinx 现场可编程门阵列 Artix-7 来完成。微处理器 32 位嵌入式微处理器用于控制磁强计并与控制系统的相邻级别进行接口。考虑到传感器的个体特性，包括偏置电压、磁灵敏度的非线性及其温度依赖性，通过根据磁场感应的原始幅度和传感器的温度计算依赖于多项式来校正所获得的数据来进行校正。多项式系数对于每个传感器都是唯一的，在校准过程中确定一次，并存储在专用的电可擦可编程只读存储器中。该磁强计具有 0.1µT 的高分辨率和不超过 6µT 的绝对测量误差。
