Fundamental Research on Surface Discharge Phenomena of Insulation Materials in space Environment

航天器充电被认为是高海拔航天器（如地球同步卫星）故障的主要原因。在模拟航天器充放电过程的高真空室中，对电子束辐照聚合物薄膜的放电现象进行了实验研究。据推测，影响航天器充放电现象的空间环境和实验室高真空室的主要区别在于残余气体的温度和压力。温度影响绝缘材料的导电性。它对充电现象起主导作用，但对放电现象的影响较小。在实验室中实现的气体压力仍然比地球同步轨道高度的空间环境高得多。由于这项研究的结果，残余气体已经被认为在表面放电中起着重要的作用。由于在表面放电起始条件和放电光谱中都存在调节效应，因此在残余气体分子少得多的空间环境中很难发生电弧放电。抚平绝缘材料与金属表面之间的界面，也有助于提高放电电位。尽管有上述发现，但实际上已观察到地球同步轨道上航天器的放电情况。这一事实表明，航天器表面绝缘材料中吸收的气体分子的释放可能是造成放电现象的重要因素。因此，真空室现象的模拟对于研究航天器的充放电是有帮助的。残余气体的分子也影响与表面放电有关的某种绝缘材料的劣化，这是通过释放气体的质谱分析知道的。在评估空间舱内的航天器材料时，必须考虑到这一事实。少

Spacecraft charging is considered a major cause of malfunctions of spacecrafts on high altitude, such as geosynchronous satellites. An experimental study on the discharge phenomena on polymer films irradiated by an electron beam in a high-vacuum chamber, which simulates the spacecraft charging and discharging, has been performed.1. Major differences between the space environment and the high-vacuum chamber in a laboratory, which affect the spacecraft charging and discharging phenomena, are supposedly the temperature and the pressure of the residual gas. The temperature influences the conductivity of insulation materials. It dominates the charging phenomena, however, it is believed to be less influential on the discharge phenomena.2. The gas pressure realized in a laboratory is still considerably higher than the space environment at the altitude of the geosynchronous orbit. As a result of this research, the residual gas has been known to play an important role in the initiation of surfa … More ce discharges. As the conditioning effect is observed in both the condition of the initiation of surface discharge and the spectrum of discharge light, the arc discharge will be harder to occur in the space environment where residual gas molecules are much less. Smoothing the interface between the insulation materials and metallic surface will also help the discharge potential to rise.3. In spite of the above findings, discharges on spacecrafts on the geosynchronous orbit have been actually observed. This fact suggests that release of gas molecules absorbed in the insulation materials on the surface of spacecrafts may be an important factor in the discharge phenomena. Therefore, the simulation of the phenomena in a vacuum chamber is known to be useful in investigating the spacecraft charging and discharging.4. The molecules of residual gas also affect deterioration of some kind of insulation material associated with surface discharges, which is known by the mass-spectrum analysis of released gas. This fact has to be taken into account in the evaluation of spacecraft materials in a space chamber. Less