雷电冲击电压下环氧树脂基频率选择超材料沿面放电特性

频率选择超材料是隐身雷达罩的理想罩体材料,内部存在大量周期性金属超结构单元,常规雷电屏蔽方法无法对其形成有效保护。该文利用环氧树脂基材制备一种频率选择超材料,研究雷电冲击电压下这种超材料表面的放电通道形貌特征,提出夹角因子参数并测量了50%沿面放电电压。在此基础上,利用夹角因子对超材料表面绝缘特性进行评估,得出沿面放电电压随偏离角变化的规律。结果表明,超材料表面放电通道呈折线型,由两类放电路径组成:第一类路径与超结构周期方向平行,第二类路径与超结构周期方向夹角45°。进一步分析发现,超材料沿面放电的主通道发生在沿绝缘间隙总长度最短的路径上。随着双电极连线偏离超结构周期方向角度的增大,沿面放电电压先增后减,当偏离角为0°或45°时,放电电压较低;当偏离角为22.5°时,放电电压较高。研究结果可为超材料隐身雷达罩的雷电防护提供参考。

Analysis of Surface Discharge Characteristics of a Frequency Selective Metamaterial Based on Epoxy Resin under Lightning Pulse Voltage

Frequency selective metamaterial is an ideal enclosure material for stealth radomes. Owing a large number of periodic metal superstructure units in the material, the conventional lightning shielding method cannot protect metamaterial effectively. In this paper, firstly, a frequency selective metamaterial based on the epoxy resin substrate was prepared and morphology characteristics of discharge channels under lightning pulsed voltage were studied. Meanwhile, the parameter of angle factor was proposed and 50% surface flashover voltage was measured. Secondly, the regulation of surface discharge voltage to deviation angle was obtained using angle factor to evaluate insulation characteristics of metamaterial. The results show that the development of discharge channels is broken line and consist of two types of discharge paths. The first type of path is parallel to the periodic direction of the superstructure units, while the second type of path is along the direction at an angle of 45°between the path and the periodic direction of superstructure units. Further analysis shows that main channels of the metamaterial surface discharge occur along the path with the shortest total length of the insulation gap. As the angle between the periodic direction of superstructure units and the connecting line of high-low electrodes increases, surface flashover voltage first increases and then decreases. When the deviation angle is 0° or 45°, surface flashover voltage is lower, while when the deviation angle is 22.5°, the 50% surface flashover voltage is higher. The research results provide theoretical reference for lightning protection on metamaterial stealth radomes.