Electric and thermal characteristics of repeated sliding electric contact interface under high pulse current

Abstract

In solid electromagnetic rail launcher, electric and thermal characteristics of sliding electric contact between armature and rails are related to contact status, current conduction and energy dissipation of sliding interface, influencing launcher system efficiency and rail lifespan. Many repeated launch test groups under different maximum linear current density were designed and carried out. Through iterative computation with test electric parameters, dynamic variation rule of sliding contact resistance and interface joule heat power were obtained, and effect of melt deposition evolvement and linear current density on electro-thermal properties were further analyzed. With inspection of melting deposition on rails after repeated tests, interface evolution process of sliding electric contact in gun bore was discussed. Results show that the steady critical point of sliding electric contact resistance and peak point of interface joule heat power both came up during current falling-edge. Contact resistance value of steady phase can be reduced in 10-2 m, and the maximum value of joule heat power can reach 10-1 MW. Contact resistance and heat power were affected hardly by repeated tests shows that deposition would re-melt and play positive role in sliding electric contact characteristic. Interface joule heat power was enlarged evidently by increasing linear current density even under the same input energy.