This paper investigates the high frequency response of the Mirnov probe based on a test platform, which is capable of generating a uniform AC magnetic field within the frequency range of 1-300 kHz. The eddy current effect is quantitatively reflected by the phase shift ϕc and normalized amplitude δ of the measured magnetic field between cases with and without a conducting plate located near the Mirnov probe. This method compensates the resonant effect in the Mirnov probe circuit and hence reflects purely the eddy current effect. The eddy current effect increases with the decrease in the distance between the probe and the conducting plate. With the increase in frequency, the magnitude of δ decreases to a saturated value at 10 kHz but increases significantly above 100 kHz for 304-stainless steel, while the eddy current effect with graphite appears at around 10 kHz and the magnitude of δ decreases to the minimum at 125 kHz, followed by a significant increase above 125 kHz. With the increase in f, the magnitude of ϕc increased until 2.5 kHz and 40 kHz for steel and graphite, respectively, then decreased with a further increase in f. The phasor expression is introduced to describe the AC magnetic field and allows an easy expression of the eddy current field. The phase of the eddy current field decreases toward -180° with f. The amplitude of the eddy current field increases with f and reaches its maximum when the skin depth reduces to a critical value. The eddy current field decreases with a further increase in the frequency.

中文翻译：

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研究涡流对 J-TEXT 上 Mirnov 探头高频响应的影响

本文研究了基于测试平台的 Mirnov 探头的高频响应，该平台能够在 1-300 kHz 的频率范围内产生均匀的交流磁场。涡流效应由相移 ϕc 和测量磁场的归一化幅度 δ 定量反映，在有和没有位于 Mirnov 探头附近的导电板的情况下。这种方法补偿了 Mirnov 探针电路中的谐振效应，因此纯粹反映了涡流效应。涡流效应随着探头和导电板之间距离的减小而增加。随着频率的增加，δ 的幅度在 10 kHz 时下降到饱和值，但对于 304 不锈钢，在 100 kHz 以上时显着增加，而石墨的涡流效应出现在 10 kHz 左右，δ 的幅度在 125 kHz 时降至最低，随后在 125 kHz 以上显着增加。随着 f 的增加，钢和石墨的 ϕc 幅度分别增加到 2.5 kHz 和 40 kHz，然后随着 f 的进一步增加而减小。引入相量表达式来描述交流磁场，并允许涡流场的简单表达。涡流场的相位随着 f 向 -180° 减小。涡流场的振幅随 f 增加，并在趋肤深度减小到临界值时达到最大值。涡流场随着频率的进一步增加而减小。随后在 125 kHz 以上显着增加。随着 f 的增加，钢和石墨的 ϕc 幅度分别增加到 2.5 kHz 和 40 kHz，然后随着 f 的进一步增加而减小。引入相量表达式来描述交流磁场，并允许涡流场的简单表达。涡流场的相位随着 f 向 -180° 减小。涡流场的振幅随 f 增加，并在趋肤深度减小到临界值时达到最大值。涡流场随着频率的进一步增加而减小。随后在 125 kHz 以上显着增加。随着 f 的增加，钢和石墨的 ϕc 幅度分别增加到 2.5 kHz 和 40 kHz，然后随着 f 的进一步增加而减小。引入相量表达式来描述交流磁场，并允许涡流场的简单表达。涡流场的相位随着 f 向 -180° 减小。涡流场的振幅随 f 增加，并在趋肤深度减小到临界值时达到最大值。涡流场随着频率的进一步增加而减小。引入相量表达式来描述交流磁场，并允许涡流场的简单表达。涡流场的相位随着 f 向 -180° 减小。涡流场的振幅随 f 增加，并在趋肤深度减小到临界值时达到最大值。涡流场随着频率的进一步增加而减小。引入相量表达式来描述交流磁场，并允许涡流场的简单表达。涡流场的相位随着 f 向 -180° 减小。涡流场的振幅随 f 增加，并在趋肤深度减小到临界值时达到最大值。涡流场随着频率的进一步增加而减小。