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.
Investigation of the Inner Conical Armature in Synchronous Induction Coilgun
Synchronous induction coilgun (SICG) has attracted more and more attention due to its advantages of simple manufacturing and no physical contact between armature and barrel. The armature, as an important component of SICG, will directly affect the launch speed and energy conversion efficiency. According to the distribution characteristics of eddy current and electromagnetic force, a new structural armature is proposed in this paper. The proposed inner conical armature is characterized by the maximum thickness at the tail end and the minimum thickness at the front end, with a gradual decrease in the thickness along the axial direction. The simulation results reveal that the proposed armature not only increases the mutual inductance between the armature and the drive coil but also enhances the electromagnetic force and weakens the armature capture effect. The experimental results verify that, compared with a traditional armature weighing 56.5 g, the new structure armature weighing 58.0 g enables higher muzzle velocities using the same set of pulsed power supply and drive coil, providing higher efficiency.
Investigations of dielectric gratings using electrodynamic models based on volume integral equations
Eigenmodes of planar and cylindrical dielectric gratings (DGs) and electromagnetic wave scattering from multiplayer DGs are investigated. The DG characteristics are calculated using numerical-analytical solution of integral equations (IEs).