Developing a more focal magnetic stimulator. Part II: Fabricating coils and measuring induced current distributions.
Developing a more focal magnetic stimulator. Part II: Fabricating coils and measuring induced current distributions.
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DOI：
10.1097/00004691-199101000-00014
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
K. Yunokuchi;David Cohen
中科院分区：
文献类型：
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作者：
K. Yunokuchi;David Cohen
首先，我们的计划制造刺激线圈的焦点进行审查。这些都是在数字8的形状，其中的目标是使他们逐步更聚焦，因此逐步较小的大小。虽然较小的线圈需要较大的脉冲电流，产生的应力和热问题，操作原型很容易制造圆直径低至2.5厘米。然而，对于较小的直径，线圈套管破裂，正在探索新的套管技术。其次，我们的程序进行审查，用于测量由刺激器线圈在盐水罐中诱导的电流分布，以确定其焦点。同轴探针测量槽中两个相邻点之间的电势差，产生局部电流密度。测量是由于几种形状的坦克和线圈配置。在球形容器中，结果证实了理论，既不能有径向电流感应球的任何地方，也没有任何电流在球的中心。在接近半无限体积和人类肢体的坦克中，由于商业“煎饼”线圈和几个8字形线圈，显示了箭头地图分布。在半无限槽中，分布也可以理论计算，测量的分布与计算一致，从而验证了测量。在肢体罐中，分布被压缩，并且比半无限罐中更聚焦，这取决于线圈方向。
First, our program for fabricating stimulator coils that are focal is reviewed. These are in the figure-eight shape, where the goal is to make them successively more focal, hence of successively smaller size. Although smaller coils require larger pulse currents, with resulting stress and heat problems, operating prototypes were readily fabricated with circle diameters down to 2.5 cm. However, for smaller diameters, the coil casings were fractured, and new casing techniques are being explored. Second, our program is reviewed for measuring the distribution of current induced in saline tanks by stimulator coils, to determine their focality. A coaxial probe measures the potential difference between two neighboring points in the tank, yielding the local current density. Measurements are presented due to several shapes of tanks and coil configurations. In a spherical tank, results confirm the theory that there can be neither radial current induced anywhere in the sphere nor any current at the sphere center. In tanks approximating a semi-infinite volume and the human limb, arrow-map distributions are shown, due to a commercial "pancake" coil and several figure-eight coils. In the semi-infinite tank, where the distribution can also be computed theoretically, the measured distribution agrees with the computations, thus validating the measurements. In the limb tank, the distribution is compressed and is somewhat more focal than in the semi-infinite tank, depending on the coil orientation.