Direct measurement of 1-mN-class thrust and 100-s-class specific impulse for a CubeSat propulsion system

Abstract

This paper presents the development of a thrust stand to enable direct measurement of thrust and specific impulse for a CubeSat propulsion system during firing. The thrust stand is an inverted pendulum and incorporates a mass balance for direct in situ mass measurement. The proposed calibration procedure allows precise performance characterization and achieves a resolution of 80 μN thrust and 0.01 g mass loss, by taking into account the drift of the thrust-stand zero caused by propellant consumption. The performance of a water micro-resistojet propulsion system for CubeSats was directly characterized as a proof of concept of the thrust stand. Continuous profiles of thrust, specific impulse, and mass consumption were acquired under various conditions in a single firing test. A thrust from 1 mN to 10 mN and a specific impulse from 45 s to 100 s with a maximum measurement uncertainty of ±15.3% were measured for the throat Reynolds number in the range 100–400.

Comparison of Submillinewton Thrust Measurements Between a Laser Interferometer and a Load Cell on a Pendulum Balance

“…One of the most typical techniques used for thrust measurement involves the concept of the pendulum. In its simplest form, a pendulum thrust balance can be based on a hanging pendulum (Charles et al, 2016;Wong et al, 2012), an inverted pendulum (Haag, 1991;Kokal and Celik, 2017;Asakawa et al, 2020), or be a torsional balance (Ziemer, 2001;Zhou et al, 2013;Soni and Roy, 2013;Little and Jugroot, 2019;Tang et al, 2011;Zhang et al, 2017). There are also more complicated implementations of this, such as the stand for vertically oriented thrust measurement system described in Moeller and Polzin (2010).…”

Impulse Measurement Methods for Space Micro-Propulsion Systems

“…Usually, the resolution is determined according to the measurement noise level, and the resolution can be specified to be twice the noise signal. The noise signal can be characterized by the ratio between amplitude and frequency or power spectral density [5,8,9,25].…”

“…The impulse generated by the micro-nano satellite propulsion system is very small, corresponding to the maximum swing angle generated α Max is smaller, at this time α max /tanα max ≈ 1. Therefore, formula (8)…”

“…Among the above five types of tests, the performance measurement test with micro-thrust and impulse measurement as the core is the main test item of the electric propulsion system. This measurement is an essential measurement link to evaluate the performance of the electric propulsion system and is also an important reference index to measure the stability of the electric propulsion system, which runs through all stages of the spacecraft, such as the single machine level, subsystem level, and the whole star level [7][8][9][10].…”

A Test Platform to Assess the Impact of Miniaturized Propulsion Systems

“…The design, integration, and the road to qualification of the Adelis-SAMSON nano-satellite cold-gas propulsion system is proposed in [19], but the focus is on component levels in the propellant tank, thruster assembly, pressure regulators, and fill and vent valves. The development of a thrust stand to enable the direct measurement of thrust and specific impulse for a CubeSat propulsion system during firing is shown in [20]: the processes, setups, and calibration phases of the ground support equipment made of an inverted pendulum that incorporates the thrust balance are detailed. An iodine-fueled RF ion propulsion system (compatible with the 6U CubeSat form-factor) is developed by Busek that performed the integration and functional test at component level ((i.e., the flight PPU subsystem, including a demonstration of thruster-cathode hot fire with the full suite of PPU breadboards) and the random vibration test of other mechanical parts (e.g., the gimbal elements) [21].…”