The Development Of High-precision Three-dimensional Geomagnetic Jerks Simulation System

Geomagnetic Jerks phenomenon,the study of long-term changes in the geomagnetic field,the magnetic field rate of change in the slope of mutation,acceleration direction of the geomagnetism is also changed,and even a few million years appeared geomagnetic field polarity reversal phenomenon.Lots of literature suggest that the Geomagnetic Jerks phenomenon occurs successively within a period of time around the world,which can be verified by geomagnetic observation data.It's a certain periodic change.Scientists at home and abroad based on Geomagnetic Jerks phenomenon is mainly focused on the analysis of its causes and time variation,regional distribution,and then to study the origin of modern geomagnetic field theory,while ignoring the long-term changes in Earth's magnetic field applied to the phenomenon of other studies.Steady geomagnetic field simulation system on the market at this stage has been shaped magnetic field is applied to the background of stricter frontier research.However,the geomagnetic field is a changing physical field,and so far the Geomagnetic Jerks phenomenon has not been applied to its research field.This paper optimizes the three-component geomagnetic jerks change model according to the timevarying characteristics of the long-term variation of the geomagnetic field.The model was put into practical use and a three-component geomagnetic emergency simulation system was developed.It provides an experimental platform to promote the development of basic scientific research or other areas of cutting-edge research.Geomagnetic field simulation systems developed by domestic and foreign research institutions are bridged by modular instruments,and their control accuracy is not high.And so far,special geomagnetic field simulation instruments have not been developed.Since the geomagnetic field signal is a weak magnetic field of 20~70 ?T,the changing magnetic field of the geomagnetic field is relatively weaker.In order to realize the simulation of the changing magnetic field,the current and magnetic field control accuracy of the system must be improved.Above all the problems,this paper proposes a design scheme of a three-dimensional geomagnetic jerk simulation system with high accuracy,high integration.The research work of this paper is as follows.Firstly,According to the time-domain characteristics of the long-term change of the geomagnetic field,this paper analyzes the composition and proportion of various magnetic source fields in the geomagnetic field model.Based on the time series prediction algorithm proposed by Brown,the three-component geomagnetic Jerks change model is optimized,and puts into practical use to develop a three-component geomagnetic jerks change simulation system.Finally,the overall design of threecomponent geomagnetic jerks change simulation system is proposed.Secondly,based on the principle of Helmholtz coils,the homogeneous magnetic field region of the rectangular coil and circular coil were discussed,the coil structure design of the three-dimensional geomagnetic jerk simulation system is analyzed,and the magnetic field finite element simulation analysis is performed on the coil structure.According to the experimental requirements and technical specifications,then,the relevant parameters are set and completed Tri-axial square Helmholtz coil structure design.Thirdly,the overall design scheme of the three-dimensional geomagnetic jerk drive system is proposed.The system uses the host computer,ARM and FPGA architecture design to carry out the drive control design of the three-component geomagnetic jerks simulation system,and that generates a numerically controlled current source with a current control accuracy of 0.1mA.The three-channel highprecision 18-bit AD5780 is used to perform data conversion on the three-component current signal.At the same time,the Howland circuit structure is used to achieve a large dynamic range of current-driven amplification,and the current output range is 0 ~ ± 2A.Finally,current and field dual closed loop feedback control design,it improve the control accuracy of the system current and the magnetic field.Finally,the experimental verification analysis of the three-dimensional geomagnetic jerk simulation system was carried out.First,the central magnetic field uniformity and uniform area generated by the coil structure were experimentally verified.And it has a spherical magnetic field uniform area with a diameter of 260 mm,while the magnetic field uniformity was 1%.Second,calibration experiments were performed on the target magnetic field and driving current of the simulation system to determine the corresponding linear change relationship between the system current and magnetic field.Third,the new simulation system has respectively performed magnetic field compensation experiments or stable geomagnetic magnetic field construction experiments in the laboratory magnetic field exposure environment or electromagnetic shielding room with the magnetic field control precision of 1 nT and the current control accuracy of 0.2 mA.Four,the experiments of geomagnetic jerk phenomenon simulation was carried out by the new simulation system to verify the rationality and effectiveness of the method.Last but not least,the new simulation system is compared with the commercial geomagnetic simulation system,which shows that the new threecomponent geomagnetic jerks change simulation system meets the technical indicators of the commercial geomagnetic abrupt change system,and meets the requirements of the research platform to simulate the geomagnetic field change environment.It provides important technical support for its frontier research fields or basic theoretical research.