电子辐照下聚酰亚胺薄膜的深层充电现象研究

空间辐射环境下聚合物绝缘材料的深层充放电效应是威胁航天器安全的重要因素之一。文章利用能量为5～100keV的单能电子枪,研究了不同束流强度电子辐照下聚酰亚胺薄膜样品的深层充电过程。实验表明,在102pA量级的电子束辐照下,聚酰亚胺薄膜样品的表面电位迅速上升后缓慢变化,最终可以达到几kV。在一定条件下,样品表面电位随着辐照电子束流密度和样品厚度的增加而增大;充电达到平衡所需的时间随着辐照电子束流密度和样品厚度的增加而减少。辐照截止后聚酰亚胺薄膜样品内部电荷的泄放需经历较长时间,由衰减时间常数推测出的样品电阻率要比采用传统测量方法得到的结果高一个量级。

A study on deep dielectric charging on polyimide film under electron beam irradiation

The deep dielectric charging effect in polymeric materials is one of the most important factors threatening the satellite's life in space environment. Deep dielectric charging process on polyimide films is studied in this paper using an electron gun with the energy ranging between 5 keV and 100 keV. Under the irradiation of electron beam with the intensity of several hundred picoamperes,the surface voltage of the polyimide film increases rapidly at the first stage and then changes slowly,reaching a final voltage of several kilo-volts,which grows with the thickness of the sample and the intensity of the electron beam under certain conditions. The charging equilibration time constant decreases with the beam intensity and the thickness of the sample. The surface voltage decays slowly when the electron beam is cut off. Resistivities obtained by charge decay method are higher than those obtained by the traditional method by one order of magnitude.