Theoretic And Experimental Study On Magnetically Driven Solid Liner Implosion

Magnetically driven solid liner implosion could drive solid metal liner to several kilometers or tens of kilometers in cylindrical configuration through the megaampere current or mega-gauss magnetic field using pulsed power facility,which also can compress interior substance to high pressure and high energy density status with a shock or quasi-isentropic manner.The magnetic pressure is in direct proportion to the square of current density that is different to other methods.Magnetism is naturally uniform which means higher symmetry on cylindrical configuration.As a typical cylindrical-convergent drive technique,magnetically driven solid liner implosion has been widely applied in hydrodynamic behavior,the dynamic characteristics of material and fusion energy and so on.The research fields include metal interface instability,surface ejecta or micro spall,material damage,converged shock wave,gas-particle flow,equation of state,constitutive relation and dynamic instability.The whole circuit model including the load-source coupling effect is established according to shin-shell model,incompressible model,electrical action model and so on,which realizes the fast optimization for load-source parameters.Based on those simplified models,the optimization of load parameters for FP1/2 facility is carried out and the influential mechanism to solid liner implosion is analyzed.The SOL1D code is accomplished via Wilkins difference schemes based on one dimensional elastic-plastic MHD basic equations,that means a more accurate analytical method is built for solid liner implosion dynamic.The accuracy and usability of the SOL1D code is proved by the experimental results of FP1 facility and ZR facility.Experimental techniques for interface instability and gas-particle flow based on FP-1 facility are established.In particular,the growth rate of MRT instability and RM instability for finite thickness solid liner is obtained which is consistent with the experimental result in FP1 facility.The pressure gradient force cannot be ignored compared with drag force under cylindrical convergent compression based on gas-particle flow theory.The capability of gas-particle simulation is established based on SOL1D code.The effect of convergence propagation and rebound of shock wave on mixture distribution is studied with gas-particle simulation,and the theoretical analysis is agree with experimental results on FP1 facility.The main conclusions and innovations of this paper are as follows:1.The system theory and design method of the simplified model for the rapid optimization of parameter range selection of solid liner and the one-dimensional elastic-plastic magnetohydrodynamic program for the fine simulation of physical experiment parameters are preliminarily established.2.Based on the FP-1 device,the experiment technology of uniform implosion on cylindrical solid liner was perfected,and the dispersion of impact time was less than 60 ns.Based on the above experimental techniques,the physical experiment and analysis methods of interface instability of solid liner implosion and gas-particle two-phase flow were developed.3.Based on the implosion perturbation analysis of thin shells,the perturbation growth formula of MRT instability with strength effect under finite thickness is derived analytically.On the basis of Mikaelian theory,this paper introduces convergence effect and carries out strength correction,and obtains the RM perturbation growth formula under pulse loading under the condition of convergence compression.4.Through SOL1D program combining gas compression experiment on FP-1 device,the compressed gas flow field in the process of convergence is obtained,and the pressure gradient force is introduced.The influence of velocity distribution and the granularity was calculated,and connecting with the coarse tin target experiment on FP-1 facility gas shock rebound from axis is the main causes for mixture thickness increase during late compression.5.It is put forward that the electrical action is not only the criterion of the physical state of the liner,but also the internal variable of the kinetic parameter(velocity).The simplified formula for calculating the implosion velocity is obtained by some hypothesis,and the rationality of the formula is verified by the implosion velocity curve of the liner experiment on FP-1 device.6.A whole circuit model with driver source-load coupling can quickly assess the impact of load parameters,structure and material properties.The results show that the smaller the fixed impedance,the greater the influence of load parameters on the loading current.When the thickness of the return column is the same as that of the liner layer,the expansion work has a significant effect on the reduction of the implosion velocity.The linear current density threshold condition is obtained analytically.When the linear current density is less than the given threshold condition,the effects of yield strength and plastic power dissipation on the velocity of implosion cannot be ignored.There are seven chapters in this paper.The first chapter is the introduction.The second chapter is a simplified model of liner implosion.The third chapter introduces the optimal design method of load parameters and presents the main mechanism affecting liner implosion.The fourth chapter introduces the programming method of SOLID.In chapter five,the perturbation growth rules of MRT instability and RM instability under cylindrical implosion are studied.In chapter six,the research results of gas-particle two-phase flow under the condition of convergence compression are introduced.Chapter seven is the summary and prospect.