Abstract
The “cubesat” form factor has been adopted as the defacto standard for a cost effective and modular, nano-satellite platform. Many commercial options exist for nearly all components re- quired to build such satellite; however, there is a limited range of thruster options that suit the power and size restrictions of a cubesat. Based on the prior work on the “Pocket Rocket” electro- thermal capacitively-coupled radiofrequency (RF) plasma thruster operating at 13.56 MHz, a new design is proposed which is based on an inductively-coupled radiofrequency plasma system operat- ing at 40.68 MHz. The new thruster design, which includes a compact and efficient radiofrequency matching network adjacent to the plasma cavity is presented, together with the first direct thrust measurements using argon as the propellant with the thruster immersed in vacuum and attached to a calibrated thrust balance. These initial results of the unoptimised first prototype indicate an up to 40% instantaneous thrust gain from the plasma compared to the cold gas thrust: typical total thrust at 100 SCCM of argon and 50 W RF power is ∼ 1.1 mN.
Highlights
Electric propulsion has been used by satellite operators for station keeping and orbit modification since the 1960’s [1]
In the typical LEO 90-min period orbit, this allows enough time to recharge the batteries between thruster operations. Using this operation scheme and the performance obtained by the inductive Pocket Rocket (PR) proof of concept presented in this study, a 2 kg cubesat in a circular 400 km orbit will gain roughly 100 m of altitude per orbit using the thruster at 100 SCCM and 50 W of RF
Essential improvements to the thrust measurement procedure have been carried out as follows: the propellant is supplied via a flexible PTFE hose with an outer diameter of 1.5 mm and inner diameter of 0.8 mm, and RF power is supplied via a flexible RF cable (RG316)
Summary
Electric propulsion has been used by satellite operators for station keeping and orbit modification since the 1960’s [1]. In the typical LEO 90-min period orbit, this allows enough time to recharge the batteries between thruster operations Using this operation scheme and the performance obtained by the inductive PR proof of concept presented in this study, a 2 kg cubesat in a circular 400 km orbit will gain roughly 100 m of altitude per orbit using the thruster at 100 SCCM and 50 W of RF. The plasma thrust gain results from two terms, a bulk plasma propellant heating thrust term (resulting from ion-neutral charge exchange collisions) which immediately takes place at turn on (first 100 ms) and a wall propellant heating thrust term (resistojet effect) which increases with burn time as a result of ion bombardment of the radial plasma cavity walls These two thrust terms have never been directly demonstrated and quantified experimentally. Instead we provide additional references cases of a cold gas system and of a filament heated resistojet system and some comparative discussion with larger low pressure inductively coupled thruster
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
