Research on the Influence of Asynchronous Coil Launcher (Coil AC Pulse Linear Motor) Shell on the Launch Efficiency

ABSTRACT The effect of a metal shell on the launch efficiency of an asynchronous coil launcher (coil AC pulse linear motor) remains insufficiently understood in terms of the underlying mechanisms and principles. To address this gap, this study conducted extensive modelling simulations and calculations, varying the shell's conductivity, permeability, and dimensions. Through comparative analysis of these models, this paper identifies a unique ‘tick‐shaped efficiency curve’ for the asynchronous coil launcher: the launch efficiency first decreases and then increases as the shell's electromagnetic parameters are enhanced. Enhancements that bolster the electromagnetic induction effect within the shell—such as increased conductivity, permeability and dimensions—are termed as the augmentation of electromagnetic parameters. This study delves into Lenz's law of electromagnetism to elucidate the observed phenomena, attributing them to the spatio‐temporal force characteristics of the multi‐peak and multi‐valley armature of the transmitting device, and the resulting ‘tick‐shaped efficiency curve’. A comprehensive summary of shell‐related research in electromagnetic emission reveals that the driving current fundamentally dictates the shell's impact on launch efficiency. DC‐driven launchers conform to the monotonic effect efficiency curve, whereas AC‐driven launchers conform to the tick‐shaped efficiency curve.