Power Optimization of a Planar Single-Channel Shim Coil for a Permanent Magnet Circuit

Terada, Yasuhiko; Ishi, Keiichiro; Tamada, Daiki; Kose, Katsumi

doi:10.7567/apex.6.026701

Cited by 8 publications

(3 citation statements)

References 9 publications

(17 reference statements)

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“…The deterioration in homogeneity can be overcome by reducing power dissipation with the combined use of the MCC method, SF method, and power optimization algorithm. Recently we experimentally showed that with a power-optimized SC shim coil, there is negligible heat generation and negligible degradation of the magnetic field in continuous use [45].…”

Section: Discussionmentioning

confidence: 99%

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

Terada

Kono

Ishizawa

et al. 2013

Journal of Magnetic Resonance

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We adopted a combination of pieces of permanent magnets and a single-channel (SC) shim coil to shim the magnetic field in a magnetic resonance imaging system dedicated for skeletal age assessment of children. The target magnet was a 0.3-T open and compact permanent magnet tailored to the hand imaging of young children. The homogeneity of the magnetic field was first improved by shimming using pieces of permanent magnets. The residual local inhomogeneity was then compensated for by shimming using the SC shim coil. The effectiveness of the shimming was measured by imaging the left hands of human subjects and evaluating the image quality. The magnetic resonance images for the child subject clearly visualized anatomical structures of all bones necessary for skeletal age assessment, demonstrating the usefulness of combined shimming.

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Section: Discussionmentioning

confidence: 99%

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

Terada

Kono

Ishizawa

et al. 2013

Journal of Magnetic Resonance

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“…14b), for which the puzzle of hardware components is on the road to completion. For example, optical hyperpolarization and NMR detection of 129 Xe have been realized on a microfluidic chip [246]; in pursuit of miniaturizing magnets, concepts for constructing small spectroscopy-grade magnets with homogeneous fields accounting for imperfection of magnet components have been found to be superior to concepts based on perfection of magnet components [247], and shimming by ablation on the atomic scale promises ultimate precision [248], so that residual and temperature-dependent magnetic field inhomogeneities can be reduced by novel concepts of electrical shimming [249,250]. Despite intriguing alternatives such as optical detection [251,252], inductive detection remains the scheme most explored in the context of miniaturization [253][254][255], where tuning to the low resonance frequencies of NMR with permanent magnets is enabled with sacrificial inductances [219], which, when fitted with a high-quality factor, can significantly boost the detection sensitivity [256].…”

Section: Miniaturization and Conclusionmentioning

confidence: 99%

Mobile and Compact NMR

Blümich

2016

Modern Magnetic Resonance

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NMR with mobile and compact devices is experiencing considerable growth in recent years in particular since instruments have become available, which are capable not only of measuring NMR relaxation but also images and highresolution spectra. Based on permanent magnet technology, compact tabletop NMR instruments measure samples of materials and solutions positioned inside the magnet, while compact mobile instruments measure material properties of intact objects and samples nondestructively in the inhomogeneous stray field outside the magnet. Following a brief introduction to NMR with homogeneous and inhomogeneous magnetic fields and to the concepts of permanent center-and stray-field NMR magnets, the evolution of the technology over the past 10 years is reviewed and illustrated with selected applications. Relaxation and diffusion measurements find use in the analysis of foods, biological tissues, polymer materials, porous media, and objects of cultural heritage. Compact imaging

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“…6,7) Finally, a designed practical electron gun with a gradual reversal of the magnetic field is used to drive the W-band sixth-harmonic magnetron-type slotted peniotron with a permanent magnet system. 8,9) Extensive efforts are underway to develop a high-frequency, high-efficiency, compact, and short-operational-gap microwave source. The high harmonic slotted peniotron with an axis-encircling electron beam is one approach, due to its advantages in high efficiency and low magnetic field requirements.…”

mentioning

confidence: 99%

A Novel Large-Orbit Electron Gun Driving a W-Band Sixth-Harmonic Magnetron-Type Slotted Peniotron with a Permanent Magnet System

et al. 2013

Appl. Phys. Express

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This paper demonstrates the operating characteristics of a W-band peniotron with a permanent magnet system. A practical novel large-orbit electron beam with axial velocity spread of 5.17%, transverse velocity spread of 1.28%, guiding center deviation ratio of 10.7%, and high average velocity ratio of 2 is designed to drive a sixth-harmonic magnetron-type slotted peniotron. Compared with the peniotron with an ideal electron beam, the output power of the practical peniotron decreases from 30 to 22 kW at 94 GHz, and its conversion efficiency correspondingly decreases from 40 to 30%. Based on a permanent magnet system, the main advantage of such peniotron is that it can have a much more compact size and lower cost, and its operational gap can be greatly reduced.

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Power Optimization of a Planar Single-Channel Shim Coil for a Permanent Magnet Circuit

Cited by 8 publications

References 9 publications

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

Magnetic field shimming of a permanent magnet using a combination of pieces of permanent magnets and a single-channel shim coil for skeletal age assessment of children

Mobile and Compact NMR

A Novel Large-Orbit Electron Gun Driving a W-Band Sixth-Harmonic Magnetron-Type Slotted Peniotron with a Permanent Magnet System

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