枢轨电接触性能随电枢膛内滑动而演变，界面电磁特性变化是其演变的根本作用因素。以系统时变电磁场计算为基础，从脉冲电流、电枢速度和局部接触等三个方面讨论了对界面电磁特性演变的作用规律，并设计实验综合验证了电枢膛内运动时枢轨电接触界面的电磁特性演变。结果表明：脉冲电流驱使电流向接触前端聚集，电流峰值聚集随电流变化而下降；电枢速度克服脉冲电流作用向接触尾部聚集电流，尾端聚集临界速度（50 m/s）下，接触表面电流分布最为均匀，高速下接触表面呈现尾端U型电流聚集模式；局部接触对电流的聚集作用随接触面增加、速度增加而减弱；在法向磁力作用下，预置接触会向前扩展并趋于稳定。实验后枢轨表面检测验证了各因素对电磁特性演变的作用规律。研究结果为深入探究枢轨滑动电接触机理奠定基础。

Performance of electric contact between armature and rails（A-R） developed as armature sliding in railgun bore, in which electromagnetic(EM) characteristics at A-R interface was the fundamental mechanism. Based on transient magnetic field calculation of railgun system, effects of three factors including pulse current, armature velocity, local contact area on evolvement rule of EM characteristics at A-R interface were analyzed. Besides, groups of launching experiments were designed to comprehensively verify the evolvement rule of EM characteristics at A-R interface. Analysis results indicated that, variation of pulse current induced tendency of current concentration towards contact front end, and decreased crowding level of surface current peak region. Armature velocity induced tendency of current concentration towards contact trailing end. Crowding level of current contact trailing end became strengthened as armature velocity increased after 50 m/s, at which current distribution on contact surface was the greatest. Mode of current concentration on the contact surface became U style close to the contact trailing end. Compared with entire surface contact, current density peak was enhanced at various local contact situations, but difference became smaller when local contact area increased or armature velocity increased. Under normal magnetic force, initial contact area would be extended forward. Effect rules above are validated through surface detection of rails and armatures after launching experiments. A-R sliding electric contact mechanism will be deeply studied based on this research results.