真空出气对星用聚酰亚胺材料电导率的影响

卫星介质材料在真空环境下的出气有可能对材料本身的介电性能产生显著影响，增加长期服役卫星寿命末期的充放电风险。文章以卫星上常用的聚酰亚胺材料为对象，通过地面90Sr-90Y辐照源加速辐照试验研究了在材料真空出气后其表面充电平衡负电位的变化，并据此计算出材料电导率的变化规律。结果显示，在5 pA/cm2电子辐照强度下，聚酰亚胺样品的电导率随着出气量的增加而明显下降，在总质量损失达到0.5%时，电导率减小一半左右。初步分析了出气导致电导率下降的物理机制。研究结果对卫星寿命末期充放电防护设计有指导意义。

Influence of vacuum outgassing on dielectric conductivity of polyimide

The vacuum outgassing of nonmetallic materials used for satellite may have a significant impact on the dielectric properties of the materials, thus increase the ESD risk of a long-term service satellite at a later stage. In this paper, the commonly-used non-metallic material (polyimide) is selected as the research object. The influence of outgassing on the surface potential of the polyimide samples is studied through the accelerated ground simulation test by a ⁹⁰Sr-⁹⁰Y radiation source, and the dielectric conductivity is calculated by curve fitting. It is found that in a high temperature vacuum environment under the 5 pA/cm² electron irradiation, the samples that have experienced longer time of degassing exhibit lower conductivity, about half of its original value at a total mass loss of 0.5%. The related physical mechanism is analyzed. The result may provide some guidance to the ESD protection design for long-lifetime satellites.