A Bond Graph Model of an Electromagnetic Launcher—Part 1: Structure and Details

An electromagnetic launcher (EML) or railgun is a complex dynamically coupled system with interacting electric, magnetic, mechanical, and thermal subsystems. This paper formulates a bond graph systems model of an EML, including capacitor bank power supply; electric and magnetic response of rails; electric, magnetic, and mechanical response of armature; magnetic containment structure for flux; electric contact resistance between sliding armature and rails; generation of forward longitudinal motion; temperatures and heat transfer in the armature and rails; armature melt wear and plasma erosion; transverse contact mechanics of armature sliding on rails; and plasma contact for armature rail separation and transition. In this paper, the bond graph model is constructed, and from the bond graph, state equations are extracted.