Numerical Simulation And Experimental Study On The Destructive Pulsed High Magnetic Field

The realization of high magnetic field has always been very tough and extremely challenging in the megagauss range.Up to now,three methods have been commonly used to generate the megagauss magnetic field: the single-turn coil,the electromagnetic flux compression and the explosive flux compression technique.The first two techniques have been widely used in the result of their easy control and good repeatability.Their discharge processes are very complicated,and refer to electromagnetism,mechanics,thermology,plasma science and etc.To simulate this process accurately,a reasonable and precise numerical model is necessary.First,the 2-D filamentary model and finite element model(including 2-D and 3-D model)of the single-turn coil technique are separately established based on the theory of circuit and electromagnetic fields.Then the deformation of the coil and the influence of the temperature and velocity on the current distribution are analyzed,and the three models are compared both in the reasonability and accuracy.Second,based on the 2-D filamentary model,the model of the electromagnetic flux compression(EMFC)in-pinch geometry is established.It takes the deformation of the driving coil into consideration,which makes the model more reasonable and accurate.According to the relationship of the induced current,the magnetic field and the motion of the coil,the distribution of current and temperature at different times are studied.And the magnetic field distribution between the two coils and the deformation of the cylinder coil are analyzed.Then,the energy relation in the stage of the flux compression is deduced,which exactly explains the existence of the optimum seed magnetic field.Third,the model of the EMFC in Z-pinch geometry is established,and the calculation of mutual inductance and magnetic pressure is studied.The generation of its magnetic pressure is analyzed,which is different from the-pinch geometry.And the change of the poloidal current and the z-direction current is explained.Then,the processes of the two different methods are compared.At last,a single-turn coil system is designed based on the pulsed power supply system.By experiments,the discharge processes on different power systems and coil sizes are compared.Then,the different explosions of coils caused by temperature and electromagnetic stress are analyzed through the 2-D FEM model.Finally,the experiment results verify the accuracy and reliability of the models,which will have important significance for the future researches.