Armature Structure Research of a Synchronous Induction Coil Launcher
Armature is very important for a synchronous induction coil launcher which can transform the electric energy to kinetic energy and push the load forward. The structure of the armature will influence the kinetic energy conversion efficiency directly. This paper analyzes the armature structure of a capacitor-driven synchronous induction coil launcher. Length and thickness of the armature are analyzed that how these parameters influence the maximum velocity and system efficiency of the launcher. Current filaments model is used to calculate the motion characteristics of a tubular linear induction motors, which is verified by an experiment and finite-element code. Genetic algorithm optimizer is used to calculate the best trigger times of the coils and the maximum velocity under the conditions of different length and thickness of the armature. It is shown that when the armature mass is fixed, length and thickness of the armature will greatly increase the velocity of the armature. The best length of the armature should be almost 2–2.5 times the length of the coil. The best thickness of the armature could be estimated by skin depth.
Study of a Multisection Synchronous Induction Coil Launcher
Synchronous induction coil launcher (SICL) has advantages of friction-free and simple control. It could be widely used in low-speed ejector and high-speed launch. While multistage SICL is hard to design due to complicated inductive coupling. Armature is often subjected to wavelike electromagnetic force (EMF), which is harmful for the sensitive load. Driving coils are difficult to construct for a large power supply. This paper proposed a multisection SICL to smooth the pull EMF, increase the thrust, and reduce the pressure of each coil. A typical two-section SICL is designed and constructed. Motion characteristics and electromagnetic properties of the launcher are analyzed based on finite-element software. The results of simulation and test are in agreement. The single-section and two-section SICL are compared to verify the feasibility of EMF enhancement. Finally, the effect of ignition time on the acceleration smoothness of the launcher is studied.
Study of coilgun performance and comments on powered armatures
Electromagnetic launch technology is being developed at Sandia National Laboratories (SNL) for applications such as high-speed transit, military defense, and space vehicle launching. A lumped-parameter circuit simulation code called Slingshot was developed by SNL to simulate launcher performance (B.M. Marder, 2001). This software calculates self and position-dependent mutual inductances, and temperature-dependent resistances to determine the electrical circuit response self-consistently with the equations of motion for the projectile. The software was designed to simulate high velocity projectile applications where an inductively driven armature was desirable. The armature is modeled as series RL circuit to represent a conductive single-turn loop or a coil winding and did not include any sources. However under some circumstances, such as lower velocity designs for missile launchers, a powered projectile may have some advantages. Such coils could be powered by a small onboard capacitor bank, batteries, or through an external supply. This paper will discuss the operation and some of the design parameters for a general coil gun as well as the circumstances under which a powered armature is desirable