Effect factors of turnoff time for shallow seafloor transient electromagnetic detecting system
ZHOU Feng-dao LIN Jun ZHOU Guo-hua LIU Chang-sheng WANG Yan (Key Lab of Geo-Information Exploration & Instrumentation (Jilin University), Ministry of Education, Jinlin Changchun 130026, China)
Transmit coils are modeled and analyzed by using circuit theory. For the transient electromagnetic exploration sysytem of shallow seafloor employing small transmit coils with many turns, the relation between the turnoff time and amplitude of transmitter current and the number of coil turns is discussed. In the precondition that the transmitter magnetic moment keeps unchange, the rule of determining the amplitude of transmitter current and coil turns to short turnoff time is presented in this paper. The experimential results testify the validity of the analysis conclusions.