Power electronic devices used in space shuttles experience degradation due to their sensitivity towards surrounding radiations. Generally, Metal-Oxide Semiconductor Field Effect Transistors (MOSFET) are used in these devices because of their fast switching speed and low power consumption capabilities. Ionizing radiation causes induced charge to build-up which damages the electrical characteristics of the MOSFET. This study investigates the threshold voltage shifts and drain current degradation for N-channel power MOSFET ZVN3320FTA by simulating experimental data on COMSOL Multiphysics. Total Ionization Dose (TID) degrade the oxide layer of MOSFETs by inducing interface-trap and oxide-trap charges. Generation of these excessive electron-hole pairs eventually causes threshold voltage shifts and current degradation. © 2018, UK Simulation Society. All rights reserved.