Experimental Verification and Research for the Distortion in the Integrated Frequency Responses of the High-Pressure Sealed Cabin and Magnetic Field Sensor  

作　　者：邓明 魏文博 金胜 叶高峰 张启升 景建恩 

机构地区：[1]Key Laboratory of Geo-detection (China University of Geosciences, Beijing),Ministry of Education [2]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences [3]School of Geophysics and Information Technology,China University of Geosciences

出　　处：《Journal of China University of Geosciences》2007年第4期310-319,共10页中国地质大学学报（英文版）

基　　金：This paper is supported by the National "863" Program in the Tenth Five-Year-Plan (No. 2002AA615020);Eleventh Five-Year-Plan (No. 2006AA09A201);the Focused Subject Program of Beijing (No. XK104910598).

摘　　要：Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.Although magnetotelluric sounding method applied to the land is advanced, there are many difficulties when it is applied to marine environment, one of which is how to lay magnetic field sensors down to the seafloor to complete measurements. To protect the magnetic field sensors from intense erosion and high pressure, suitable high-pressure sealed cabins must be designed to load them. For the consideration of magnetic measurement and marine operation, the sealed pressure cabin should be nonmagnetic and transportable. Among all optional materials, LC4 super.hard aluminum alloy has the highest performance of price/quality ratio to make the sealed pressure cabin. However, it does not mean that the high-pressure sealed cabin made using LC4 will be perfect in performance. In fact, because of its weak magnetism, the pressure cabin made using LC4 has distorting effect on frequency responses of the magnetic field sensors sealed in it. This distorting effect does not affect the use of the magnetic field sensor, but if we want to eliminate its effect, we should study it by experimental measurements. In our experiment tests, frequency sweep magnetic field as excitation signal was used, and then responses of the magnetic field sensor before and after being loaded into the high-pressure sealed cabin were measured. Finally, normalized abnormal curves for the frequency responses were obtained, through which we could show how the high-pressure sealed cabin produces effects on the responses of the magnetic field sensor. Experimental results suggest that the response distortion induced by the sealed pressure cabin appears on mid- and high-frequency areas. Using experimental results as standardization data, the frequency responses collected from seafloor magnetotelluric measurements can be corrected to restore real information about the seafloor field source.

关 键 词：marine magnetotellurics magnetic field sensor high-pressure sealed cabin frequency response experimental test 

分 类 号：P714[天文地球—海洋科学]