Abstract: Using experimental techniques,the paper investigates the transmitted magnetic moment,the turn-off time,and the change of induced signal with the turns of the transmitter and receiver loops of multi-turn small coincident configuration,respectively.Comparison is made between the two experimental methods,i.e.changing the receiver loop turns with fixed transmitter loop turns and vice versa,to find out the turns more suitable to geological response.Meanwhile,comparative test is done using the wire frame of loop length of 0.5m?0.5m and 1m?1m,respectively.Through the analyses on the transmitted magnetic moment,the turn-off time,the relations of induced signal intensity with the loop turns and the length,we find the reasonable small multi-turn coincident loop configuration.The result indicates that the transmitted magnetic moment increases with the increased transmitter loop turns and length;the turn-off time increases proportionally with the transmitter loop turns,but has nothing to do with the receiver loop;and the induced signal intensity has a proportional relation with loop turns,with the receiver loop turn to be dominant,comparatively.

Key words: Transient Electromagnetic Method, small coincident loop, turn-off time, transmitted magnetic moment

摘要： 文中采用实验方法对瞬变电磁法多匝重叠小回线装置发射磁矩、关断时间、感应信号强度随发射线圈匝数及接收线圈匝数的变化分别进行了研究。对固定发射线圈匝数改变接收线圈匝数与固定接收线圈匝数改变发射线圈匝数这2种实验方式进行了对比,从而找出了更适合地质响应的发射与接收线圈的匝数。同时还分别采用线圈边长为0.5m×0.5m与1m×1m的线框进行了对比实验,通过分析发射磁矩、关断时间、感应信号强度随线圈边长、线圈匝数的变化,找到合理的重叠小回线装置。实验结果表明发射磁矩随线圈的边长与发射线圈匝数的增加而增加;关断时间随发射线圈匝数近乎呈正比增加,与接收线圈无关;感应信号强度与线圈匝数呈正比关系,但是相比之下,接收线圈匝数更占主导地位。

关键词: 瞬变电磁法, 重叠小回线, 关断时间, 发射磁矩