中文摘要：

在固体电枢电磁轨道炮系统中，保持电枢轨道界面良好的电接触至关重要。在电流处于上升沿的发射起始阶段，往往可以观察到电枢材料熔化沉积集中在轨道的外侧，这表明该阶段电流在电枢边沿集中的特性。为此，利用ANSYS软件，在改变轨道电阻率和高度的条件下，对电枢电流密度的分布进行了数值仿真，仿真结果表明：1）电流集中在电枢尾翼边沿；2）通过提高轨道电阻率或者（同时）减小轨道高度可以减小电枢尾翼边沿的电流密度。在20mm方口径轨道炮上进行了实验，研究了不同电阻率的轨道材料（如98％铜-1％锆-1％铬合金，黄铜和非磁性不锈钢）和不同轨道高度（50、30mm）对电枢熔化的影响。实验结果表明，在电流上升沿，更高的轨道电阻率和更低的轨道高度时有相对较小的电枢边沿熔蚀。基于数值分析和实验结果，提出了电磁轨道炮起始阶段（电流上升沿阶段）减小电枢边沿熔蚀的轨道结构改进方案。

英文摘要：

Keeping good electrical contact between armature and rail is an important issue in solid armature railgun sys- tem. At the start stage of railgun launching with current ramp-up, the appearance of aluminum coating tends to be concentrated on the out sides of rails, which indicates current concentration on the edge of armature. Consequently, using a finite element code ANSYS, we numerically simulated armature＇s current density distribution with rails of various resis- tivity and heights. The results show that： （1） current concentrates on edges of armature tail; （2） the current density on edge of armature tail can be reduced by increasing rail resistivity and/or decreasing rail height. Moreover, we performed launch experiments in 20 mm square caliber railgun, and investigated rail materials with different resistivity, such as 98%Cu-1%Zr-1%Cr alloy, brass, and non-magnetic steel, as well as those with different heights of rail such as 50 mm and 30 mm. The results show that higher resistivity and lower height of rails have comparatively lighter armature edge ero- sion at current ramp-up. Based on above work, an improved rail structures are proposed.