Simulation of the magnetic field generated by square shape Helmholtz coils

Hurtado-Velasco, Ronald; González-Llorente, Jesús

doi:10.1016/j.apm.2016.06.027

Cited by 26 publications

(14 citation statements)

References 16 publications

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“…As expected, the quadrature birdcage coil demonstrated the most uniform B 1 + field within the brain, aided by its 16‐rung design. Although performing adequately, the clamshell transmit coil showed increased B 1 + inhomogeneity, consistent with a Helmholtz pair, which is problematic for hyperpolarized studies with non‐renewable magnetization. Additionally, the increased B 1 + requirements for carbon applications may impose limitations on short duration and adiabatic pulses, highlighting the power inefficiency associated with linearly polarized fields .…”

Section: Discussionmentioning

confidence: 99%

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain

Autry

Gordon

Carvajal

et al. 2019

Magnetic Resonance in Med

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Purpose To compare the performance of an 8‐channel surface coil/clamshell transmitter and 32‐channel head array coil/birdcage transmitter for hyperpolarized 13C brain metabolic imaging. Methods To determine the field homogeneity of the radiofrequency transmitters, B1+ mapping was performed on an ethylene glycol head phantom and evaluated by means of the double angle method. Using a 3D echo‐planar imaging sequence, coil sensitivity and noise‐only phantom data were acquired with the 8‐ and 32‐channel receiver arrays, and compared against data from the birdcage in transceiver mode. Multislice frequency‐specific 13C dynamic echo‐planar imaging was performed on a patient with a brain tumor for each hardware configuration following injection of hyperpolarized [1‐13C]pyruvate. Signal‐to‐noise ratio (SNR) was evaluated from pre‐whitened phantom and temporally summed patient data after coil combination based on optimal weights. Results The birdcage transmitter produced more uniform B1+ compared with the clamshell: 0.07 versus 0.12 (fractional error). Phantom experiments conducted with matched lateral housing separation demonstrated 8‐ versus 32‐channel mean transceiver‐normalized SNR performance: 0.91 versus 0.97 at the head center; 6.67 versus 2.08 on the sides; 0.66 versus 2.73 at the anterior; and 0.67 versus 3.17 on the posterior aspect. While the 8‐channel receiver array showed SNR benefits along lateral aspects, the 32‐channel array exhibited greater coverage and a more uniform coil‐combined profile. Temporally summed, parameter‐normalized patient data showed SNRmean,slice ratios (8‐channel/32‐channel) ranging 0.5‐2.00 from apical to central brain. White matter lactate‐to‐pyruvate ratios were conserved across hardware: 0.45 ± 0.12 (8‐channel) versus 0.43 ± 0.14 (32‐channel). Conclusion The 8‐ and 32‐channel hardware configurations each have advantages in particular brain anatomy.

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Section: Discussionmentioning

confidence: 99%

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain

Autry

Gordon

Carvajal

et al. 2019

Magnetic Resonance in Med

View full text Add to dashboard Cite

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“…A magnetic field generated by electric current can be treated as a macroscopic current in wire. Considering a current element, the magnetic field B at a given point P is obtained by Biot–Savart law and can be expressed as [ 12 , 13 , 14 , 15 , 16 ].

where

is the vector from the differential current element generic field point P .…”

Section: System Designmentioning

confidence: 99%

A Magnetic Field Canceling System Design for Diminishing Electromagnetic Interference to Avoid Environmental Hazard

Song

Lin

Manikandan

et al. 2022

IJERPH

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Electromagnetic interference is a serious and increasing form of environmental pollution, creating many issues in the areas of health care and industrial manufacturing. The performance of high-precision measurement equipment used in health care and the manufacturing industry is sensitive to electromagnetic interference. However, extremely low-frequency magnetic fields (ELFMF), with a frequency range from 3 to 30 Hz, generated by high-power lines have become the main interference source in high-tech foundries. This paper presents a magnetic cancelling system that works by combining active cancelling technology and passive cancelling technology to reduce the ELFMF around high-precision measurement equipment. The simulation and experimental results show the validity and feasibility of the proposed system.

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“…They can be configured in square, circular or triangular types. In this work, we have preferred to use square Helmholtz coils as they are known to exhibit better uniformity [10], [11]. The choice was also defined by easiness in manufacturing process.…”

Section: A Helmholtz Coilmentioning

confidence: 99%

A Magnetic Sensor Calibration System Based on a Closed-Loop Tri-Axial Field Simulator

Ramdas

Sethunadh

2022

IEEE Access

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Magnetism is an omnipresent phenomenon with potential applications in various fields. Immense research has gone into the ways in which magnetism can be used for practical applications. Apart from day-to-day applications such as mobile phones, laptops, railways etc., it finds applications in the aerospace sector as well, for interplanetary studies, navigation, and space robotics. Accurate sensing of the magnetic field is essential for these applications, for which efficient magnetic sensors are used. The precise calibration of these sensors is necessary to quantify various parameters and associated uncertainties to ensure accuracy. For this, a field simulator which can generate a highly accurate and controlled magnetic field is essential. The design and development of a Tri-axis Helmholtz coil field simulator based on Model Reference Adaptive Controller (MRAC) is presented here. It provides a simple, compact, and cost-effective solution for aerospace magnetic sensor calibration. The proposed system offers a uniform magnetic field with 0.1% uniformity within a cubic volume space of 3375cm 3 . The intensity of the magnetic field can be varied within the full-scale range of 200µT with a resolution of 0.01µT by appropriate current control. The MRAC was finalized after a detailed analysis with various types of controllers such as basic PI, PID and LQI, as it provides precise closed loop control and field stability, which is of paramount importance for aerospace magnetic sensor calibration. It exhibits lesser computational complexity, lower settling time, better adaptability to external field disturbances, lesser overshoot and higher phase margin indicating better closed loop stability compared to other controllers.

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Simulation of the magnetic field generated by square shape Helmholtz coils

Cited by 26 publications

References 16 publications

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain

A Magnetic Field Canceling System Design for Diminishing Electromagnetic Interference to Avoid Environmental Hazard

A Magnetic Sensor Calibration System Based on a Closed-Loop Tri-Axial Field Simulator

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Simulation of the magnetic field generated by square shape Helmholtz coils

Cited by 26 publications

References 16 publications

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized 13C imaging of the human brain

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized 13C imaging of the human brain

A Magnetic Field Canceling System Design for Diminishing Electromagnetic Interference to Avoid Environmental Hazard

A Magnetic Sensor Calibration System Based on a Closed-Loop Tri-Axial Field Simulator

Contact Info

Product

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Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain

Comparison between 8‐ and 32‐channel phased‐array receive coils for in vivo hyperpolarized ¹³C imaging of the human brain