Design of a Pendulum Based Micro-Thrust Measuring Device Application to Plasma Microthrusters

Pulsed laser plasma propulsion is an emerging technology in the aerospace domain. Throughout years, many researchers were investing in this topic in order to enhance and optimize the thrust. Plasma propulsion is based on the laser ablation process, where a highly energized laser beam hits the surface of a material and causes phase changes until reaching the plasma state which will expand and generate a thrust and a corresponding displacement on the ablated material. The main challenge in this type of applications is the quantification of the micro-thrust generated by the plasma plume during a very short time. The aim of this paper is to present a new pendulum based design with a resolution of $0.981\mu N$ and an accuracy of 18%. The nano-displacements induced by micro-thrusts are measured via an interferometer device and processed using a computational image processing algorithm. The device is calibrated by applying a known force using a calibrated force application device, simulating in this way the plasma ablation thrust.