As a natural result of the electrified integration and electrical energy revolution, the electromagnetic launch (EML) technology will be inevitably used for future launch missions. This paper has summarized research focuses in this field according to the published papers on EML in China during the past decade and mainly introduced the current research and progress in several key technologies, including launcher, integrated launch package, high-power high-density supply, and overall control/maintenance. Some common pressing problems are pointed out to provide direction for the application of EML technology in engineering and many other fields, such as launcher life, miniaturization of power supply, and improvement of energy availability.

Research Progress of Electromagnetic Launch Technology

The structure and trigger control strategy have become the most important factors that restrict the performance of the multistage synchronous induction coilgun (MSSICG). However, it is still a difficult task to design MSSICG under overload constraint due to coupling between the multiple parameters. In this paper, the maximization of the emission efficiency and acceleration stationarity is treated as a multiobjective optimization problem. By analyzing the relationship between the number of turns and the other structural parameters of the launch, the multiobjective optimization model of MSSICG is established by the current filament method which was verified by the experimental data and finite-element method. And then the second generation nondominated sorting genetic algorithm (NSGA-II) and multiobjective particle swarm optimization (MOPSO) were employed to optimize the model in order to maximize the energy transfer efficiency while achieving the smooth acceleration of the armature. With the formulated optimization model, a five-stage synchronous induction coilgun is optimized as a special case. A decision-making procedure based on the fuzzy membership function is used for obtaining best compromise solution from the set of Pareto-solutions obtained through NSGA-II and MOPSO. In addition, the optimization performance of the proposed multiobjective optimization model and the single-objective optimization model of the MSSICG was compared. The result of optimization shows that the proposed multiobjective optimization model of MSSICG can effectively improve the performance of the coilgun compared with the single-objective optimization model which takes of the launch velocity and overload acceleration as the combination objective function or only the launch velocity.

Multiobjective Optimization of Multistage Synchronous Induction Coilgun Based on NSGA-II

A coilgun is an electromagnetic launcher based on electromagnetic induction. The projectile with a heavy load can be accelerated to a high speed. The currents that flow through the driving coils and the projectile would produce joule losses. All of the properties are drastically determined by the geometry and power of a coilgun. This paper aims to optimize the geometry and power parameters of the coilgun. The muzzle velocity is selected to be the objective when the temperature rise limitations are taken into consideration. To analyze the performance, an equivalent circuit model including the calculation of temperature rises is employed. The performance of a three-stage coilgun is calculated based on this model and then this coilgun is optimized with the utility of adaptive genetic algorithm taking the influence of temperature rise into consideration. The result of optimization shows that the muzzle velocity is improved and the temperature rises are conformed to the design requirements. The optimized coilgun is simulated by the finite-element method to verify the performance.

Geometry and Power Optimization of Coilgun Based on Adaptive Genetic Algorithms

To make launch weapons with further range, higher energy density, better target accuracy, and better control ability are the aims pursued by people for many years. This paper divides the history of launch technology into four stages, which are the biologic, mechanical, chemical, and electromagnetic launch stages. The development trend of the launch technology is discussed, particularly the advantages of the electromagnetic launch (EML) technology. Recently, China has paid great attention to many new technical fields, such as the EML technology. China's programs are mainly confined to fields of basic research, which are collected together in this paper. However, the numbers of papers published from the 12th symposium to the 16th symposium suggest that there are more and more programs in the EML field.

The Development of EML Technology in China

This paper discusses the design and electromagnetic analysis of an induction-type coilgun system with a pulse power module. The voltage, current, force, velocity, acceleration, and efficiency of the coilgun system were analyzed using the finite-element method (FEM). A simplified FEM model was developed for ensuring both accuracy and rapid calculation times. Based on the results of the electromagnetic analysis, the geometry of the coilgun system was defined with the Taguchi method. The coil-type armature was applied for increasing the mutual inductance and projectile force. The electromagnetic analysis results were also compared with the analytical analysis results. The designed coilgun system was found to exhibit high energy efficiency and safety of the system. The design specifications and analysis results concerning the coilgun can, hence, be effectively utilized to develop a large-scale multistage induction-type coilgun system.

Design and Electromagnetic Analysis of an Induction-Type Coilgun System With a Pulse Power Module

An improved large-caliber synchronous induction coilgun was tested to demonstrate the launch of 120-mm projectiles. This induction coilgun is made of 15 identical coils. The coils are stacked end-to-end forming a barrel, and each coil is energized by the same pulsed power topology in sequence to generate a magnetic force to accelerate the projectile. Tracking of the projectile location during launching provided precise feedback to control. A computer simulation based on the viewpoint of FEA software is developed to predict the performance of the launcher system. 5-kilogram copper projectiles were accelerated from rest to 220 m/s through the 2.5-m launcher assembly with a projectile kinetic energy to capacitor stored energy efficiency of 14.5 %. The 15-stage induction coilgun provides a significant improvement in the armature capture effect, system efficient and coil structure. Further experiments studies are being continued.

Honghai Zhang

Papers

Design and testing of a 15-stage synchronous induction coilgun