Validation of an Ion-Thruster Grid Thermal Model with Experiments

Ion-thruster grid temperatures were measured in a beam-off condition to validate a grid thermal model, which calculated temperatures over the grids from voltages, currents and a temperature of each grid’s edge. The model was validated only by the data on the accel grid because those on the screen grid were found unreliable. Though parameters such as the emissivity of grids’ surface had been undetermined, the emissivity was obtained through the validation and the other undetermined parameters were found to have little effects on the results. The temperatures over the grids can be calculated using this model even in a beamon condition and the gap between the grids can be calculated from the temperatures by solving a thermo-elastic equation.