COMPENSATION OF PERTURBATIVE EFFECTS ON A THRUST MEASUREMENT MEMS PROBE FOR ELECTRIC PROPULSION

A quartz force sensor is being developed to measure the thrust of an electron cyclotron resonance (ECR) plasma thruster. This microelectromechanical system (MEMS) is immersed in the plasma jet produced by the thruster. At this location, it is subject to thermal heating, ion sputtering, and electrostatic charging effects. It also creates a Debye sheath that can change the thrust measurement. These perturbations cause a drift in the force measurement. Using a Finite-Element modeling of the MEMS probe, several sensor designs have been simulated in order to test different methods for reducing the thermal thrust drift. The use of an additional electrode on the sensor can reduce the effect of temperature gradient across the sensor by an order of magnitude. Moreover, a quartz temperature sensor enable to compensate the offset. Numerical simulations show that the thrust drift is reduced by 50% with this method.