【作者】 陈晓东；

【导师】 魏文博；

【作者基本信息】 中国地质大学（北京） ， 地球探测与信息技术， 2006， 博士

【摘要】 高温超导磁强计具有可直接测量磁场、低噪声、频带宽、低频响应好的特点。它可用于瞬变电磁法的接收传感器,实现直接测量磁场的目的。本文对高温超导磁强计研制取得的成果作了系统的论述,内容包括:高温超导磁强计研制、野外与感应线圈的对比试验、磁场数据的采集、磁场数据的分析处理、杜瓦带宽对测试的影响、与瞬变电磁仪联机参数设定等。主要研究成果如下:研制出了低噪声、宽频带、高摆率并具有较高稳定性、适合瞬变电磁法的单分量高温超导磁强计。采用屏蔽技术解决了高频信号的传输、衰减、放大等关键问题,研制出了高温超导磁强计的关键部分—前置放大器,提高了高温超导磁强计的稳定性;采用前置放大器与控制电路分离,减少了干扰,提高了仪器的实用性。研制的单分量高温超导磁强计的指标是:1、磁场噪声 100 fT /Hz;2、摆率 1m T /S;3、带宽 0～30kHz。研制出了既能手动调节又能自动调节的三分量高温超导磁强计样机。采用光耦隔离技术、屏蔽技术以及错开三个通道工作频率的方法,减少了数字电路与模拟电路的干扰和三分量之间的串扰,研制出了较稳定的三分量高温超导磁强计;采用微型计算机控制技术和 A/D、D/A 转换技术,实现了三分量高温超导磁强计的自动控制,提高了工作效率。研制出了高频无磁杜瓦,填补国内空白。采用具有迭层、独立单元的杜瓦绝热技术,避免绝热层金属薄膜在瞬变电磁一次场激发下产生涡流,消除杜瓦对测量的影响。大量的野外试验表明:高温超导磁强计性能稳定,满足瞬变电磁法要求,在瞬变电磁法中应用高温超导磁强计能够提高勘探深度。实现了高温超导磁强计在瞬变电磁法中的实用化,为深部隐伏矿以及油气勘查提供新的地球物理手段。高温超导技术在瞬变电磁法中的成功应用也是高温超导技术应用的一项重要成果。更多还原

【Abstract】 The high temperature radio frequency superconducting quantum interference device(HTS RF SQUID) magnetometer is characterized by direct measurements of magneticfields, low noise, broad bandwidth and excellent low frequency response. Theconventional induction coil could be replaced with the HTS RF SQIUD as receiving sensorfor Transient Electromagnetic ( TEM ) meters, therefore realizing direct measurements ofmagnetic fields in TEM surveys. A systematic study on the development of HTS RFSQUID magnetometer to TEM method has been carried out, including the development ofthe HTS RF SQUID magnetometer, field comparison tests between sensors by respectivelyusing HTS RF SQUID and conventional induction coil, field magnetic data acquisition,magnetic data analyses and processing, influence of Dewar bandwidth on measurements,as well as setting parameters as the HTS RF SQUID sensor is connected to a TEM meter.The achievements made through the study are as following:A HTS RF SQUID magnetometer, featuring low noise, broad bandwidth, high slewrate and high stability, has been developed, which is suitable for measuringsingle-component magnetic field in TEM surveys. The critical problems relating totransmission, attenuation and amplification of high-frequency signals have beensuccessfully solved by adopting shielding technique. A preamplifier, the key unit for theHTS RF SQUID magnetometer, has been developed, making the stability of themagnetometer significantly improved. By separating the preamplifier from the controlunit, the magnetometer has been made fewer interferences and more practical. Thespecifications of the single-component HTS RF SQUID magnetometer developed throughthe study are as 1. magnetic noise – 100 fT /Hz;2. slew rate – 1 mT/S;and 3.bandwidth – 0 ~ 30 kHz.A prototype of three-component HTS RF SQUID magnetometer has also beendeveloped, which can be adjusted either manually or automatically. With such techniquesas optical coupling isolation, shielding and staggered frequencies adopted for the threechannels, the interferences for both digital and analogue circuits and the crosstalk amongthe three channels have been significantly reduced, so making the vector HTS RF SQUIDmagnetometer more stable. By adopting techniques of microcomputer controlling andA/D and D/A converting, the automatic control for the vector HTS RF SQUIDmagnetometer has been realized, resulting in the increase of field survey efficiency.A high-frequency non-magnetic Dewar has been developed, so filling in the gap inthis field in China. The heat-isolating metal film was cut in strips to avoid vortex excitedby the primary field of TEM, and thus the influence of Dewar on measurements waseliminated.A lot of field experiments show that the HTS RF SQUID magnetometer is of highstability, meet the requirements of TEM surveys and with its detection depth increased.To further make the HTS RF SQUID magnetometer practical would provide a new tool forexplorations for deep concealed deposits and oil and gas, making this advanced hightemperature superconducting technique turn into productive force in geophysicalexploration.更多还原