| 时间域航空电磁系统探测深度研究 |
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| 引用本文： | 韩雪,殷长春,任秀艳,刘云鹤,张博,蔡晶.时间域航空电磁系统探测深度研究[J].吉林大学学报(地球科学版),2019,49(5):1448-1456. |
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| 作者姓名： | 韩雪 殷长春 任秀艳 刘云鹤 张博 蔡晶 |
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| 作者单位： | 吉林大学地球探测科学与技术学院, 长春 130026 |
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| 基金项目： | 国家重点研发计划项目（2016YFC0303100，2017YFC0601903，2018YFC0603300）；中央级公益性科研院所基本科研业务费专项经费项目（JYYWF20180103）；国家自然科学基金项目（41530320，41774125）；中科院先导专项（XDA14020102） |
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| 摘 要： | 时间域航空电磁系统探测深度与采样时间、发射磁矩、大地电导率、仪器背景噪声和灵敏度等诸多因素相关。本文基于时间域航空电磁一维正演对时间域航空电磁系统探测深度进行研究。正演算法从麦克斯韦方程出发，结合准静态近似条件，得到一维层状介质上空中心回线频率域电磁场响应的垂直分量，并采用汉克尔积分进行计算，进而通过时-频变换获得时间域电磁场响应。探测深度研究参考仪器背景噪声水平，通过设定最小可识别信号阈值（本文设定为系统背景噪声三倍）获取最大可探测分离时间，进而利用该分离时间结合平均电导率求取最大探测深度。最后本文以VTEM系统为例，对不同层状介质模型以及不同发射磁矩、背景噪声、发射脉宽和飞行高度下的时间域航空电磁系统最大探测深度进行分析和讨论。
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| 关 键 词： | 时间域 航空电磁 探测深度 噪声水平 |
| 收稿时间： | 2018-08-24 |
Research on Exploration Depth of Time-Domain Airborne EM System |
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| Han Xue,Yin Changchun,Ren Xiuyan,Liu Yunhe,Zhang Bo,Cai Jing.Research on Exploration Depth of Time-Domain Airborne EM System[J].Journal of Jilin Unviersity:Earth Science Edition,2019,49(5):1448-1456. |
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| Authors: | Han Xue Yin Changchun Ren Xiuyan Liu Yunhe Zhang Bo Cai Jing |
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| Institution: | College of GeoExploration Science and Technology, Jilin University, Changchun 130026, China |
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| Abstract: | The exploration depth of a time-domain airborne electromagnetic (EM) system is closely related to many factors such as sampling time, transmitting dipole moment, earth conductivity, instrument background noise,and sensitivity. This study is about the exploration depth of time-domain airborne EM systems based on time-domain one-dimensional forward modeling. The forward algorithm starts from the Maxwell equation and combines the quasi-static approximation conditions to obtain the vertical component of the EM field response in the frequency domain of the central loop over a one-dimensional layered medium. Hankel integral is used to calculate the EM responses in frequency-domain and then obtain the time-domain responses via time-frequency transform. We set the minimum identifiable signal threshold to be three times of the system background noise level to obtain the maximum detectable departure time, from which we obtained the maximum depth of exploration with the average conductivity. Finally, taking the VTEM system as an example, we analyzed and discussed the maximum exploration depth of airborne EM system in the time domain under different layered media models and different transmission magnetic moments, background noise, transmission pulse width and flight altitude. |
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| Keywords: | time-domain airborne EM exploration depth noise level |
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