关键词: 瞬变电磁法, 重叠小回线, 关断时间, 发射磁矩

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