电子辐照下接地方式及工作电压对聚醚酰亚胺内带电特性的影响

Influence of Grounding Mode and Working Voltage on the Internal Charging Characteristics of Polyetherimide Under Electron Irradiation

为了探究高能电子辐照下接地方式及高工作电压与沉积电荷共同作用对介质内部充电性能的影响,提出了一种三维介质内带电评估方法。首先采用Geant4软件模拟高能电子与介质的作用过程得到对应的电荷沉积速率及剂量率,再通过有限元方法求解三维电荷输运方程得出介质内的电场分布,最后以聚醚酰亚胺为研究对象,计算了不同接地方式、工作电压下介质内电场分布。结果表明:电子辐照下,接地方式主要影响接地面积及沉积电荷到接地侧的最大传输距离;增大接地面积、减小电荷传输距离能有效降低介质内电场强度。工作电压对介质内电场的影响取决于施压方式及电压,当工作电压从100 V增大到5000 V,样品正面悬浮、底面加压(S-V_(S))或正面加压、底面悬浮(V_(S)-S)时,介质内电场强度最大值相差不大且均不随工作电压变化,稳定在3.04×10^(7) V/m;样品正面接地、底面加压(G-V_(S))时,内电场强度最大值从2.1×10^(7) V/m减小至1.78×10^(7) V/m,而正面加压、底面接地(V_(S)-G)时,最大电场则从2.11×10^(7) V/m增大到2.50×10^(7) V/m。综上,高工作电压下可以增大聚醚酰亚胺样品的接地面积并采用正面接地、底面加压的施压方式来降低其内部放电风险。

An evaluation method for the 3-D dielectric is proposed to explore the effects of grounding mode and interaction of high working voltage and deposited charge on the internal charging performance of the dielectric under electron irradiation.Firstly,Geant4 software is used to simulate the interaction process of high-energy electrons and the dielectric in the space environment to obtain the corresponding charge deposition rate and dose rate,and then the charge transport equation is solved by a finite element method to obtain the electric field distribution in the dielectric.Then,the distribution characteristics of electric field in polyetherimide under different grounding modes and working voltages are calculated.The results show that the grounding mode mainly affects the grounding area and the maximum transmission distance between the deposited charge and the grounding electrode,which implies that,increasing the grounding area or reducing the charge transmission distance can effectively reduce the internal electric field of the dielectric.The influence of the working voltage on the internal electric field in the dielectric depends on the voltage applying method and the voltage value.When the voltage increases from 100 V to 5000 V,the electric field in the dielectric remains unchanged at 3.04×10^(7) V/m in the cases of S-V_(S)(i.e.suspending the irradiation side while applying voltage on the other side)and V_(S)-S(i.e.applying voltage on the irradiation side while suspending the other side);the maximum internal electric field strength decreases from 2.1×10^(7) V/m to 1.78×10^(7) V/m in the case of G-V_(S)(i.e.grounding the irradiation side while applying voltage on the other side),and increases from 2.11×10^(7) V/m to 2.50×10^(7) V/m in the case of V_(S)-G(i.e.applying voltage on the irradiation side while grounding the other side).It is concluded that the grounding area of polyetherimide sample can be increased under high working voltage,and the G-V_(S) voltage applying mode can be used to reduce the risk of internal discharge.