OPTIMIZED SMALL-BORE, HIGH-PASS RESONATOR DESIGNS

被引:34
作者
CROZIER, S [1 ]
LUESCHER, K [1 ]
FORBES, LK [1 ]
DODDRELL, DM [1 ]
机构
[1] UNIV QUEENSLAND,DEPT MATH,ST LUCIA,QLD 4072,AUSTRALIA
来源
JOURNAL OF MAGNETIC RESONANCE SERIES B | 1995年 / 109卷 / 01期
关键词
D O I
10.1006/jmrb.1995.1140
中图分类号
O64 [物理化学(理论化学)、化学物理学]; O56 [分子物理学、原子物理学];
学科分类号
070203 ; 070304 ; 081704 ; 1406 ;
摘要
The radiofrequency field homogeneity and quality factor (Q) of a number of high-pass resonator designs are compared theoretically and experimentally for small-bore coils. It was found that for high-pass resonators with the number of distributed capacitors greater than eight, a significant and unacceptable decrease in Q resulted. A number of schemes are proposed and investigated to improve the homogeneity of eight-capacitor high-pass resonators, thus balancing Q and homogeneity. These designs include variation in rung width, interrung feeding, a new hybrid coil design, and the use of internal guard rings. Eleven high-pass resonators were modeled and built to test the designs. The current density in each conductor was calculated using a novel numerical technique based on the inverse finite Hilbert transform which implicitly includes the effects of RF eddy currents. It was found that the effect of such eddy currents is important in coils of small geometry. RF fields were calculated from the current densities by using a retarded-potential solution to the free-space Maxwell equations. The interrung-fed hybrid coil design with guard rings was found to be superior to conventional designs. (C) 1995 Academic Press, Inc.
引用
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页码:1 / 11
页数:11
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