In this paper, an approach to the design of shielded radio-frequency （RF） phased-array coils for magnetic resonance imaging （MRI） is proposed. The target field method is used to find current densities distributed ...In this paper, an approach to the design of shielded radio-frequency （RF） phased-array coils for magnetic resonance imaging （MRI） is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coll＇s winding pattern, the selection of a penalty factor is discussed in detail.展开更多
A new 7.0 T asymmetric active shield superconducting magnet for Penning traps is proposed in this work. The magnet has two field regions whose homogeneity is better than 0.5 ppm. Linear and nonlinear methods are used ...A new 7.0 T asymmetric active shield superconducting magnet for Penning traps is proposed in this work. The magnet has two field regions whose homogeneity is better than 0.5 ppm. Linear and nonlinear methods are used for the asymmetric electromagnetic optimization. Stress analysis, mechanical design and a quench protection system design are also introduced in this paper.展开更多
基金Project supported by the National Nature Science Foundation of China (Grant No. 30900332)Grant of General Administration of Quality Supervision Inspection and Quarantine of China (Grant No. 201210079)+1 种基金the Program for Science and Technology Department of Zhejiang Province, China (Grant Nos. 2010C14010 and 2010C33172)the Natural Science Foundation of Zhejiang Province, China (Grant No. Y2090966)
文摘In this paper, an approach to the design of shielded radio-frequency （RF） phased-array coils for magnetic resonance imaging （MRI） is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coll＇s winding pattern, the selection of a penalty factor is discussed in detail.
基金Supported by National Natural Science Foundation of China(11302225)
文摘A new 7.0 T asymmetric active shield superconducting magnet for Penning traps is proposed in this work. The magnet has two field regions whose homogeneity is better than 0.5 ppm. Linear and nonlinear methods are used for the asymmetric electromagnetic optimization. Stress analysis, mechanical design and a quench protection system design are also introduced in this paper.
