Development of thrust stand for low impulse measurement from microthrusters

A thrust stand has been developed to accurately measure thrust produced by two types of microthrusters—a liquid propellant pulsed plasma thruster (LP-PPT) and a diode laser ablation microthruster. The impulse of LP-PPT ranged from 20 to 80 μNs. The diode laser microthruster, which is a new type of microthruster, produces much lower impulse range of 1–10 μNs for about 1 s. The mechanical noise induced from the background vibrations becomes a crucial problem for precise estimate of thrust particularly in low impulse measurements. A data analysis method to reduce the effect of mechanical noise is proposed by introducing an additional term in a fitting function. It was verified that the analysis method used in our experimental conditions reduced variance caused by noise down to one-third that of a normal fitting method. The accuracy of the thrust stand is 2.1 μNs in the case of the LP-PPT and 0.7 μNs in the case of the diode laser microthruster.