scholarly journals LADRC-Based Magnetic Field Measurement Method for a Nuclear Magnetic Resonance Rotation Sensor

2021 ◽  
Vol 11 (21) ◽  
pp. 10458
Author(s):  
Xinghua Zhao ◽  
Zhanchao Liu ◽  
Xinda Song ◽  
Jianli Li ◽  
Yibo Shao
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Measurement ◽  
Magnetic Field Measurement ◽  
Loop Control ◽  
Rotation Sensor ◽  
Resonance Rotation ◽  
Phase Loop ◽  
Nuclear Magnetic

Magnetic field measurement is fundamental to nuclear magnetic resonance rotation sensors (NMRRS). A phase-locked loop (PLL)-based measurement with two nuclear isotopes is commonly applied to observe the magnetic field. However, the phase-loop and frequency-loop of the nuclear isotopes cannot be optimized simultaneously by a PLL-based method. In this paper, an approach based on a linear active disturbance rejection controller (LADRC) is proposed for synchronous phase-loop control of the two nuclear isotopes. Meanwhile, the frequencies of the nuclear isotopes are observed by linear extended state observers (LESOs). The phase and frequency loops can be decoupled and optimized with the proposed method. An experimental NMRRS prototype used for verification is built. The effectiveness and the feasibility of the proposed method are validated with the experimental results.

Diamagnetization in the Vortex State of Bi(Pb)-Sr-Ca-Cu-O: Magnetic Field Measurement at the Surface by Nuclear Magnetic Resonance

1991 ◽  
Vol 30 (Part 2, No. 4A) ◽  
pp. L572-L575 ◽  
Author(s):  
Yutaka Maniwa ◽  
Hiroshi Sato ◽  
Taku Mituhashi ◽  
Kenji Mizoguchi ◽  
Ikuyo Shiozaki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Measurement ◽  
Vortex State ◽  
Magnetic Field Measurement ◽  
Nuclear Magnetic

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

Design of Braunbeck Coil for Nuclear Magnetic Resonance Gyro Magnetic Field Excitation

2018 ◽  
Vol 23 (6) ◽  
pp. 740-745
Author(s):  
Pei Wang ◽  
Hua Liu ◽  
Xiang Cheng ◽  
Wanliang Zhao ◽  
Shaoliang Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Excitation ◽  
Nuclear Magnetic

scholarly journals The development of the magnetic system of sensor for PMR-analyser

2020 ◽  
Vol 22 (4) ◽  
pp. 115-122
Author(s):  
A. Y. Svinin ◽  
R. S. Каshaev ◽  
O. V. Коzelkov
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic System ◽  
Scientific Paper ◽  
Magnetic Sensors ◽  
Measuring Instruments ◽  
Main Task ◽  
Magnetic Field Homogeneity ◽  
Nuclear Magnetic

The enhancement of the measuring instruments accuracy has always been the most crucial task for engineers and scientists. In particular, in the field of nuclear magnetic resonance, the creation of uniform magnetic field often defines the results of measurements, therefore the main task of this study is to develop Halbach magnet array based on design characteristics of developing NMR-analyzer. The research describes the development process of the main sensor’s magnetic system components for continuous-flow portable NMR-analyzer. The scientific paper makes a different variations analysis of Halbach magnet arrays on the degree of the magnetic field homogeneity, shows the process of development and production of the 3D-framework for Halbach magnet array for NMR-analyzer. The article also gives information on the design of quartz generator based on Pierce oscillator circuit for receiver-transmitter coil of the NMR-analyzer’s sensor. The results could be useful for the magnetic sensors design with high degree of homogeneity, measuring instruments and devices using the method of nuclear magnetic resonance in its foundation.

scholarly journals Cross-Axis Coupling Effects in Single-Axis Nuclear Magnetic Resonance Gyroscopes

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 734
Author(s):  
Zhiguo Wang ◽  
Yi Zhang ◽  
Xiang Zhan ◽  
Qiyuan Jiang ◽  
Hui Luo
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Vibration Frequency ◽  
Coupling Effects ◽  
Rotation Rates ◽  
Angular Vibration ◽  
The Cross ◽  
Cross Axis ◽  
Nuclear Magnetic

Nuclear magnetic resonance gyroscopes (NMRGs) may be operated in an environment with violent vibration that usually contains both linear components and angular components. To analyze the influence of angular vibration on an NMRG, cross-axis coupling effects are studied. The cross-axis rotation rates induce an equivalent magnetic field. Its influence can be described by the Bloch equations. The approximate frequency shift and amplitude of the spin oscillator with an equivalent magnetic field in the cross-axis were obtained, which was validated by numerical simulation. The findings show that the angular vibration component leads to a remarkable error for the NMRG. When the angular vibration frequency is near the Larmor frequency, the oscillation frequency of the spins may be locked to the angular vibration frequency, destroying the NMRG’s ability to measure rotation rates. The cross-axis coupling problem should be considered in the design of an NMRG and corresponding inertial navigation systems.

scholarly journals Effective Suppression of Residual Magnetic Interference in a Conductive Shielded Room for Ultra-Low Field Nuclear Magnetic Resonance

2020 ◽  
Vol 10 (11) ◽  
pp. 3745
Author(s):  
Yiqiu Tan ◽  
Danfeng Zhou ◽  
Mengxiao Song ◽  
Jie Li
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Eddy Currents ◽  
Small Scale ◽  
Signal Loss ◽  
Low Field ◽  
Residual Magnetic Field ◽  
Control Electronics ◽  
Nuclear Magnetic

Residual magnetic interference induced by applied magnetic field pulses inside a conductive shielded room (SR) has been a common issue in ultra-low-field (ULF) nuclear magnetic resonance (NMR). The rapid cutoff of the applied pre-polarizing field (Bp) induces eddy currents in the walls of the SR, which produces a decaying residual magnetic interference that may cause severe image distortions and signal loss. In this study, a pair of cancellation coils (CC) and control electronics were designed for the suppression of the residual magnetic interference in a SR. Simulations show that this method was effective in suppressing the residual magnetic field (Br) after removal of the pre-polarizing magnetic field. Then, a small-scale SR was designed and the effectiveness of this cancellation scheme was experimentally verified. The test results showed a good agreement with the simulation, which indicated that the cancellation scheme was capable of reducing Br field to a much lower level. The scheme proposed in this study provides a solution for suppressing the residual magnetic field in the ULF NMR system. After decoupling the eddy–current field, the effect of the suppression may be further improved by optimization of the cancellation coil in further work.

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