针对空腔中B-dot的频响特性开展了分析。当频率低于一定值时,安装在空腔中的B-dot探头的输出信号存在低频分量增益,可以用一个“负时间常数的RC高通滤波器”描述其频响特性,其本质是低频段为增益的高通滤波器。采用不同等效频率的RLC回路连接安装B-dot的传输线,开展了B-dot探头低频响应的实验研究,结果表明,被测信号等效频率不同时,标定得到的磁通穿透特征时间常数以及互感系数有所不同。因此,为得到正确的修正系数,应当使标定波形的等效频率尽量接近实测波形。

The frequency response of B-dot monitors fielded in the cavity of magnetically-insulated transmission lines is analyzed. The equivalent sensitivity of B-dot monitors in the cavity could be increased at low frequencies. The B-dot monitor behaves approximately as if its signal were transmitted though a high-pass RC filter with negative RC time constant, and the lower frequency components are amplified. The experiments were carried on at different equivalent frequencies. It shows that both the characteristic flux-penetration time and the mutual inductance between the main circuit and the B-dot monitor are different while the frequency of the test signal is changed. The equivalent bandwidth of calibration waveform should approach the real waveform to get the exact correcting coefficients.