High-power constant current technique for the excitation source of electromagnetic exploration on land
In the field of geophysical exploration, one of effective methods to detect buried metal ores is multiple-frequency fusion electromagnetic excitation and its imaging. This technique needs to set a high-power artificial EM source in subsurface of the target area. To facilitate supply of such a large power, a constant current of high-voltage is necessary. However, some factors such as heterogeneities of subsurface media, property of excitation polarization and variations of the natural EM field can make terrestrial impedance change with time, so that the output current will be unstable and data collection will be influenced. To solve this issue, this paper presents a kind of high power constant current technique based on the excitation of generator. We describe its implement method and operating principles in detail, and display the schematic circuit diagram. The result of the experiment shows that this technique is feasible and its constant current precision can meet the requirement of electromagnetic exploration.