Development of a Thrust Stand to meet LISA Mission Requirements

A thrust stand has been built to measure the force-noise produced by electrostatic microNewton (µN) thrusters. The LISA mission’s Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 µN with a resolution of 0.1 µN. The stationary force-noise produced by these thrusters must not exceed 0.1 µN/√Hz in the measurement bandwidth 10 -4 to 1 Hz. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from 10 -4 to 1 Hz with 0.1 µN/√Hz sensitivity, absolute thrust measurements from 1-100 µN with better than 0.1 µN resolution, and dynamic thruster response from 10 -4 to 10 Hz. The LTS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.