航空瞬变电磁三分量空心线圈传感器设计

Design of Airborne Transient Electromagnetic Three-component Hollow Coil Sensor

航空瞬变电磁法(ATEM)是地球物理勘探中的主要方法之一,被广泛应用在油气、地下水等深地资源的勘查。瞬变电磁接收系统一般采用感应式空心线圈传感器接收瞬变电磁信号,其具有本身重量轻、固有线性频率的特点。线圈传感器仅对垂直于其孔径的磁通敏感,为了确定矢量磁场的所有方向分量,此次传感器设计成三个相互垂直的线圈。通过分析感应线圈灵敏度、信噪比等参数,对线圈尺寸、绕线方式进行了优化设计;选定本底电压、电流噪声较小的放大器,设计了接收信号前置放大电路。所研发的三分量ATEM感应式磁传感器工作带宽可达25 kHz,X、Y、Z三分量的本底噪声分别保持在:11.7、10.7、10.6(单位:nV/√Hz@1kHz),在其谐振频率处的灵敏度分别为4.3、6.5、6.4(单位:mV/nT)。本设计实现了高灵敏度三分量信号的采集,X、Y、Z三个分量完全对称分布,电参数基本一致,降低了传感器的本底噪声,有效地提高了灵敏度和信噪比。

The airborne transient electromagnetic method(ATEM)is one of the main methods in geophysical exploration,which is widely used in the exploration of deep earth resources such as oil,gas and groundwater.Transient electromagnetic receiving system generally adopts induction hollow coil sensor to receive transient electromagnetic signals,which has the characteristics of light weight and inherent linear frequency.The coil sensor is only sensitive to the magnetic of the flux perpendicular to its aperture.In order to determine all the directional components of the vector magnetic field,three mutually perpendicular coils are designed to form the sensor.By analyzing parameters such as sensitivity and signal-to-noise ratio of coil,the coil size and winding mode were optimized.By choosing the amplifier with low background voltage and current noise,the preamplifier circuit of receiving signal is designed.The working bandwidth of the developed three-component ATEM induction magnetic sensor can reach 25 kHz.The background noise of X,Y and Z components are 11.7,10.7 and 10.6 respectively(unit:nV/√Hz@1 kHz),and the sensitivity at the resonant frequency are 4.3,6.5 and 6.4 respectively(unit:mV/nT).This design realizes the acquisition of high sensitivity three-component signal.The three components of X,Y,and Z are completely symmetrically distributed,and the electrical parameters are basically the same.The sensor reduces the background noise of the sensor and effectively improves the sensitivity and signal-to-noise ratio.