高灵敏度的全自动低值磁通测量系统

An Automatic Measurement Apparatus for Low Value Magnetic Flux of High Resolution

介绍了一种高灵敏度的全自动低值磁通测量方法。对于从测量线圈得到的感应电动势信号利用了高灵敏度的纳伏计作为前置放大器进行放大 ,因而测量低值磁通的分辨率达到了 1n Wb,比国外同类仪器高出了 10倍。同时还研制了 V/ F变换器及数字积分器作为后续的积分系统 ,消除了常用的 RC积分放大器法无法避免的回复误差。包括激励电源在内的测量仪器构成了一个基于计算机的全自动测量系统 ,使用十分方便。这样的低值磁通测量系统配上一个探测线圈时可探测很微弱的磁场。当探测线圈的磁面积为 0 .2 m2 (直径 1cm,匝数约为 40 0 0 )时 ,探测弱磁场的分辨率可高达 5 n T。

An automatic measurement apparatus of high resolution for low value magnetic flux is described. A nanovoltmeter as the preamplifier is used for the induced signal from measuring coil. Thus a high resolution of 1nWb for flux measurement is reached. It is 10times higher than the similar foreign apparatus. At the same time, a V/F converter and a digital integrator are followed to obtain the flux value to avoid the returning error of the ordinary RC integral amplifier. This measuring system including the necessary exciting current source is o- perated automatically by a computer. Such a low magnetic flux measurement system may also be used for measu- ring low magnetic field with an adequate measuring coil. When the magnetic area of the measuring coil is about 0.2m 2(1cm in diameter and about 4000turns), the resolution for magnetic field detection is 5nT.