Phase Division and Critical Point Definition of Electromagnetic Railgun Sliding Contact State

Sliding contact of electromagnetic railgun affects launch accuracy, launch efficiency, and rail life. The research on sliding contact of electromagnetic railgun is very important to the theory and engineering design. However, the whole process of electromagnetic launch is high speed and big current and high heat. The state of sliding contact is complicated. The whole process is also transient process. The stage division of sliding contact is vague, and there is no definite definition about stage division. In this paper, the theoretical analysis of sliding electric contact process is introduced, and the design test is carried out to verify it. The whole launch process of electromagnetic railgun is divided into three stages: dry friction contact, liquefied layer contact, and high-speed unstable contact. The line density 15 kA/mm is defined as the critical point between dry friction stage and liquefaction stage. The armature speed 1300 m/s is defined as critical point between the liquefied contact layer and the high-speed unstable contact stage, which provides reference for the study of sliding contact in the future.