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The reconnection electromagnetic launcher is a type of induction launcher whose propulsive force is the interaction between the eddy current induced in the projectile and the pulsed high magnetic field generated by the coil. A three-stage reconnection electromagnetic launcher system has been fabricated and tested. Box-shaped helical coils are constructed to launch the flat-plate projectile. Capacitor banks are used as the power supplies. Triggered vacuum switches (TVS) are used instead of spark gaps as the closing switches because of the advantages such as small volume, no maintenance and low electromagnetic interference. Owing to the special arc extinguishing performance of TVS, energy saving potential is studied. When the arc extinguishes at the second current zero, the remaining energy of the capacitor banks contributes to higher efficiency. Index Terms--Arc extinguishing, electromagnetic launch, reconnection, triggered vacuum switch.

In this paper, we first describe the wide application of catapults, and then develop a novel electromagnetic catapult that is made up of linear brushless dc motor, describing its basic design process, analyzing various kinds of parameters of the novel linear motor, and finally using finite-element software to simulate and optimize the catapult. In addition, we also develop the test prototype machine whose length is 1 m, and it can make velocity of 6.75 kg projectile reach 10 m/s. By comparing the simulation with the experimental data, the result is satisfactory. Thus, we verify that the novel catapult is feasible further. Finally, we present the key technologies and the corresponding solution of practical application. Thus, the applied foundation has been made through the above analysis. Index Terms--Catapult, electromagnetic launch, finite element, linear motor.

Active electromagnetic armor accelerates the projectile by electromagnetic force, which could be launched to the aggressor missile on its way to protect the object. A solid metal projectile is usually applied in the active electromagnetic armor based on the elements of reconnection launch gun. A novel active multihollow-projectile electromagnetic armor is proposed in this paper based on the research of the reconnection launch gun. Given the same drive coil and pulsed power, the hollow projectile has higher kinetic energy than the solid one, and it can be filled with the detonator, which will be detonated when the projectile hits the aggressor missile. Each projectile's kinetic energy of the multiprojectile structure may be lower than the single projectile, but the general efficiency could be greatly improved. The thickness of the projectile could be designed by finite-element simulation, with the precondition of mechanical strength of the projectile. Index Terms--Active, electromagnetic armor, electromagnetic launcher, reconnection.

A solid metal plate is often used as the projectile in reconnection electromagnetic launcher. Yet, the performance is not optimum. In this paper, analysis is made about the laws of influence on magnetic field distribution of driving coils by using projectiles with different figures and materials. Further analysis is made about the influence on launching velocity of the aforementioned factors. A single-stage reconnection electromagnetic launcher is made. Experiments are carried out separately on latticed projectiles, hollow projectiles, aluminum projectiles, iron projectiles, and copper projectiles. Some significant conclusions are drawn. Under the same condition, hollow projectiles achieve the highest velocity, while latticed projectiles have a weaker shielding effect upon magnetic field. The magnetic permeability and electric conductivity of material have a great influence upon launching velocity. Based on magnetic domain theory, qualitative analysis is made about the causation of magnetic hysteresis loss, classical eddy current loss, and abnormal loss. As the loss under high-frequency alternating magnetic field increases rapidly, ferromagnetic materials are not suitable here. The electric conductivity of projectiles, as well as the thickness and the density, makes sense to launching velocity. As the frequency grows higher in pulsed magnetic field, the influence from thickness and electric conductivity of projectiles becomes weaker. Therefore, hollow projectiles made up of aluminum material which has a higher electric conductivity and a lower density will be the best choice. [ABSTRACT FROM AUTHOR]

Projectiles in coil gun usually make one-way movement and move at a very high speed. The device would be fit for the application of oil pumping unit, as long as the projectiles can make reciprocating movement and move slower by adopting proper control methods. At present, during the production process of petroleum, the efficiency of the system is rather low. Energy dissipation takes a considerable ratio in the total cost of oil production. Moreover, beam pumping-unit system suffers from long driving chain, poor flexibility, a quite huge capacity and weight under long length of stroke, and low efficiency. Aiming at the earlier problems, linear electromagnetic oil pumping unit is presented in this paper, which is essentially a multiphase coil launcher. Analysis is made about the advantages and disadvantages of three~phase and multiphase structures, as well as the practical structure. Simulation studies are made; meanwhile, experimental investigations are carried out on a small-scale-model machine system. Further simulation studies of coil launching system are carried through the mechanical and mathematical models of rod string in a sucker-rod pumping-unit system. Theoretical analysis and experimental results verify the feasibility and the validity of the proposed system. Thus, a new path to solve the problem of high energy dissipation in oil production is explored. [ABSTRACT FROM AUTHOR]

The reconnection electromagnetic launcher utilizes the interaction between the projectile eddy current and the coil magnetic field to accelerate the projectile. A reconnection launch experimental system using the box-shaped helical coils and the flat-plate projectile has been fabricated. Capacitor banks are used as the power supplies. The inductance gradient curve-fitting is performed on the basis of the measured data from the launch apparatus. Based on the circuit equation and the motion equation of the reconnection electromagnetic launch, the numerical simulation model of the projectile motion is established. The simulations show that the launch efficiency decreases when the projectile velocity increases in the multi-stage launch if every stage is kept with the same parameters. To solve the problem, an optimization for the multi-stage launch is presented. The oscillating cycle of the circuit current in each stage is determined according to the projectile velocity, from which the capacitance of the capacitor bank is determined further. Combined with the use of triggered vacuum switches (TVS) as closing switches and owing to the special arc extinguishing performance of the TVS, the projectile velocity can be increased and the launch efficiency can be improved greatly. [ABSTRACT FROM AUTHOR]