Analysis of high specific impulse Hall Thrusters
- Paper number
IAC-05-C4.P.01
- Author
Mr. Diego Escobar, Universidad Politecnica de Madrid, Spain
- Coauthor
Mr. Eduardo Ahedo, Universidad Politecnica de Madrid, Spain
- Year
2005
- Abstract
In the last decade the so-called Hall Thruster in its different configurations has been regarded as an interesting alternative to traditional chemical satellite propulsion systems. These engines are particularly suitable for orbit adjustment, station-keeping and many other applications due to its relatively high specific impulse and efficiency. They are based on the use of electromagnetic forces acting on plasma to induce a closed drift in electrons that, in turn, ionize the propellant, typically Xenon, and to accelerate the resulting ions inside the ionization chamber (ceramic walls in the Stationary Plasma Thruster, SPT, version). Both commercial and scientific missions have already implemented successfully this type of thrusters (Telstar, MBSAT). In particular, ESA launched in 2003 the SMART-1 mission to reach the Moon using this technology as primary propulsion system. Its recent success opens new opportunities for the use of these engines in future planetary missions (e.g. ESA´s BepiColombo to Mercury). However, further improvements related to efficiency, performance and operational life are required to achieve these goals and some of the most promising configurations in relation to this are dual-mode and double-stage thrusters. The former configuration can operate in the high specific impulse and low thrust regime efficiently, but also in the high thrust and low specific impulse regime when required. On the other hand, the latter configuration uses an intermediate electrode for efficiency enhancement. The present work consists on a review of these two configurations and an extension of an existing 2D PIC-hybrid numerical model called HPHall developed at the Massachusetts Institute of Technology and further improved recently at ETSIA. This code must be extended in order to model properly double ionization of the propellant since high specific impulse requires operation at high voltage where this phenomenon plays an important role and is thought to be the reason for the efficiency decrease found at this regime. In addition to this, non-ceramic walls must be introduced into the code in order to represent intermediate electrodes which is the main idea of the double stage configuration. Another important modification is related to the sonic boundary condition at the anode of the thruster placed at the back of the ionization chamber. Currently, the numerical model deals with this condition in a simplified manner and some modifications are required to better model the plasma behavior. Once these improvements are implemented, numerical results will be obtained, analyzed and compared with experimental results for different configurations in order to get a better understanding of the main physical phenomena involved. In addition to this analysis a 3D model of the Hall thruster being used in the SMART-1 mission (called PPS-1350 and developed by Snecma Moteurs) has already been created with Solid Edge v.14. This model is based on designs from different publications and the main parts of the engine (ionization chamber, anode, magnetic field circuit, coils, etc.) are represented on it in detail. Therefore it can be of great interest for inexperienced people in order to understand how the thruster works.
- Abstract document