Research On Load Current Measurement Technology Of Electromagnetic Implosion Device Based On Magneto-optic Effect

Pulse power technology is a kind of electromagnetic physical technology that uses energy storage elements to store the electromagnetic energy of lower power and releases it to the load in an instant to obtain high power pulse.Electromagnetic implosion is the use of ultra-large pulse current generated by pulse power technology to form Lorentz force to drive load implosion,it can create high energy density physical experiment conditions such as strong radiation,strong magnetic field,high temperature,high pressure and high density under the laboratory conditions.It is not only one of the possible technical ways to achieve inertial confinement fusion,but also an important means to carry out high energy density physics research such as nuclear explosion effect simulation,high-pressure dynamic properties of materials and other basic scientific research,which is of great significance for the frontier physics research of weapon fusion physics,dynamic characteristics of weapon materials,radiation physics and effects,fusion energy and astrophysics.The pulse current flowing through the load is the most important technical index of the electromagnetic implosion device.It is not only an important index to measure the energy transmission efficiency of the pulse power system of the electromagnetic implosion device,but also the magnitude and waveform shape of the pulse current directly affect the physical process and energy conversion efficiency of the electromagnetic implosion,which plays a decisive role in the electromagnetic implosion.However,due to the extremely large pulse current,the load is in the region of strong electromagnetic field and plasma recombination.At present,the current monitoring methods in common use are affected by strong space electrons,plasma,shock vibration and strong electromagnetic interference in the near-load area,so they cannot give direct measurement results.Therefore,the measurement of the current flowing through the electromagnetic implosion load has always been a worldwide problem,which has become the focus of research in this field,and has not been broken through so far.At present,in the large-scale electromagnetic implosion devices at home and abroad,the current of the transmission line near the load is usually measured as the substitute data of the load current,which leads to some errors in the relevant theoretical analysis and is difficult to evaluate effectively.Therefore,it is very urgent and necessary to explore new testing methods.The topic of this dissertation is proposed according to this urgent need.In order to solve this problem,this dissertation looks for a breakthrough point in the field of transient photoelectric sensor,and uses the characteristics of optical signal intrinsic insulation to overcome the interference of complex environment.The dissertation proposes a new design idea to measure the load current flowing through the electromagnetic implosion based on the magneto-optical effect.Through numerical simulation of the electromagnetic field distribution in the load area,the real environment of current measurement is determined,which lays the foundation for meeting the conditions of magneto-optical measurement;in this dissertation,a reflective polarization modulation magneto-optical measurement method is proposed,and the data processing method of pulse high current is studied,The key parameter linear birefringence in magneto-optical measurement was analyzed.A magneto-optical measurement system is established,and experiments are carried out on the electromagnetic implosion device with different load current levels.The work of this dissertation provides a new method to solve the problem of direct measurement of the load current of the electromagnetic implosion device.At the same time,the load current waveform is obtained through measurement,which provides more accurate experimental data for the design of the electromagnetic implosion experiment,index judgment and precise physical experiment.The innovation of this dissertation includes the following points.Firstly,the design idea of directly measuring the load current of electromagnetic implosion is put forward,the measurement system is established,and the verification experiment is carried out under different current level devices and different composite electromagnetic environment,which proves the reliability of the measurement method;secondly,a new type of reflective polarization-modulated magneto-optical measurement technology is proposed.The magneto-optical fiber sensor probe adopts the reflective design,which can not only improve the sensitivity of measurement,but also effectively reduce the influence of temperature,mechanical disturbance,stress-strain and other reciprocity effects on the effective signal.At the same time,the signal light is divided into two channels by energy splitting,which expands the dynamic range of current measurement.Thirdly,the experimental method of step-by-step verification of different current devices is proposed,which improves the reliability of measurement method and data processing.The direct measurement results of the load current flowing through the MA-level electromagnetic implosion device are given for the first time.