Mode Study And System Design Of Multipole Electromagnetic Launcher

Electromagnetic launch (EML), sometimes called electromagnetic propulsion, is suggested as that uses electromagnetic force to propel or drive objects according the interaction between magnetic field and current. The launch goal is to accelerate objects to high speed or hypervelocity. Electromagnetic launch has such advantages as no launch mass limit, high muzzle velocity, and simplified energy source, higher launch efficiency, and good working performance, easily controllable and large variety of launch structure. The most promising application for electromagnetic launch is used by the military weapons, scientific research, spaceflight and transportation, and civil industry has extensive application potential.According to the difference of launcher structure and working mode, conventional electromagnetic launcher is divided into three types:rail launcher (Railgun), coil launcher (Coilgun) and reconnection launcher (Reconnection gun). For the requirements of big mass and huge propulsion force transportation, conventional electromagnetic launchers have some principle limitations and confront several technique troubles. The two parallel rails and armature of rail launcher are working in the current of megampere, and they endure huge thermal and magnetic stress impact in the launch transient. That always causes the rails ablation and interface erosion. Intrinsically, the hypervelocity motion and electric contact friction are inherent contradiction. The coaxial solenoid coil launcher has greater radial component of electromagnetic force, represented as radial compress force or distension force. The axial force of coil launcher used to accelerate the projectile is much littler than the radial force and the utilizable efficiency of electromagnetic force is not high. For the first time in the world, this paper presents a new idea of radial magnetic field interacting with azimuthal current for electromagnetic launch, and proposes a novel multipole field electromagnetic launch mode. This paper gives the system design and analyses the performance of multipole field electromagnetic launcher.Firstly, the paper analyses the dynamics of coil launcher, and gives the mathematic model of rail launcher and coil launcher. The key techniques of conventional electromagnetic launch mode are indicated and improved. Then, the idea of radial magnetic field interacting with azimuthal current to launch object is presented and the concept of multipole electromagnetic launcher. The multipole electromagnetic launch mode is established and the multipole magnetic field configuration is mathematical resolved. The mathematical model and mechanical-electric equations of multipole electromagnetic launch mode are obtained. The solution method of system equations is presented. After the theoretical analysis, the transient launch process of multipole electromagnetic launcher is simulated with electromagnetic field finite element method (FEM). The simulation results of single stage octapole field electromagnetic launcher with catapult coil indicate that multipole electromagnetic field launcher conquer the shortcoming of conventional coil launcher, which with less axial component of electromagnetic force used to accelerate the projectile. Moreover, the multipole coils provide a restoring force for the projectile which could keep the projectile maglev and accelerate stability. Then, the three stage appositional octapole field electromagnetic launcher is simulated and analyzed. The simulated results indicate that acceleration performance of multistage launcher is obvious acceptable, and the launch mode has the potential of hypervelocity to expand with multi stages. In the end, an improved launch mode called multi-stage twisty multipole electromagnetic launcher is presented. Then three-stage twisty octapole field electromagnetic launch system is designed and simulated. The theoretic analysis and simulation results indicate that this launch mode makes the projectile with spinning motion, which improves the flying stability of projectile motion. This part of paper also gives the design of power supply circuit, detect and control system. The group power supply mode of multipole coils is proposed. Finally, the optimal design and match of pulsed current wave with discharge position is presented.Multipole electromagnetic field launch mode could improve the acceleration performance of conventional coil launcher, and they fit for large mass and big caliber projectile to accelerate to high speed and high kinetic energy. Multipole electromagnetic field launcher has the advantage of huge thrust force, high exit velocity and steady maglev characteristic. We suggest this launch mode could be applied in the transportation locomotive, designed as multipole electromagnetic levitated trains. This train has the potential of high speed, over loading, stabilization and efficiency. Furthermore, multipole electromagnetic field launch mode could be used in the field of spaceflight engineering, and designed as satellite and space shuttle's launch equipment. This launcher could easily achieve large mass and hypervelocity launch.