Electric field and charge profiles of electron beam irradiated PMMA until breakdown using Kerr electro-optic measurements

We have been developing Kerr electro-optic field mapping measurement techniques in electron beam irradiated polymethylmethacrylate (PMMA). In the previous reports, we have shown numerous light maxima and minima resulting from the accumulated trapped charge recorded on videotape and analyzed using a computerized image digitization system to obtain the charge and field profiles [1,2]. In this report, a further investigation of electric field and charge profiles using the Kerr effect is reported for energetic electron beam penetration into short circuited PMMA slabs in vacuum to simulate the space environment for a specific time or until breakdown takes place. Breakdown mechanisms and charge dynamics during the electron beam irradiation in PMMA are discussed. Radiation induced conductivity (RIC) of PMMA obtained from the short circuited current measurements during charging is also discussed.