The work carried out, stated through project specific objectives, is summarized below:
SO-1. "Study and refinement of the application cases of a high-power Hall thruster system and consolidation of the system design and requirements."
A value analysis has been performed, to identify specific missions that can take advantage from the use of a 20 kW EPS. A set of specifications was then identified and consolidated. After a specific trade-off analysis dedicated to the system architecture, the design of the Electric Propulsion System (EPS) was performed, based on the value analysis and the mission cases assessed. The system architecture and relevant requirement specifications have been assessed and consolidated at the d-PDR milestone.
SO-2. "Advancement of the electric propulsion system units and characterizing their behaviour in coupled configuration."
The project has matured the design of each subsystem of a 20 kW Hall EPS, to set the ground to qualification and to future in-orbit demonstration. The activities dedicated to the design of the subsystems (Flow Management System (FMS), Thruster Unit (TU) and Power Architecture (PA)) started with the analysis of trade-offs and the identification of relevant requirements at subsystem level. The design has been consolidated with a dedicated CDR for each unit. The units were manufactured and assembled. Test activities dedicated to verification of the design of the FMS, the TU and the PA have been performed. Finally, a coupling test of the full EPS has been successfully performed, resulting in the verification and update of the requirements.
SO-3. "Develop a set of analysis and simulations tools in order to predict the system behaviour in the long term."
ASPIRE has developed alternative qualification strategies, based on advanced numerical tools, aimed at reducing the significant cost and time requirements of a qualification campaign of a 20kW Hall thruster system. The academic Partners in the Project team, each with unique expertise and capabilities in advanced computational and experimental analyses of plasma propulsion systems, collaborated to achieve the expected progress. During the EPS coupling test the plume data necessary for the first validation of the developed simulation tools have been obtained, demonstrating good agreement with simulation results.
SO-4. "Characterize the system at different background pressures and with alternative propellants."
The effect of alternative propellants (Kr) on thruster and cathode performance and discharge stability as well as on the facility background pressure and on plasma-S/C interactions has been investigated through simulations and test. Numerical and simulation tools have been developed to assess facility effects: the set-up of the “thruster + facility” conditions has been defined, and simulations have been run. The TU has been also ignited and characterized in the range of 7-20 kW 300-400 V operating with argon, demonstrating full compatibility with this propellant, too.
SO-5. "Sketch a roadmap for in-orbit demonstration of the high-power electric propulsion system, based on the existing Space Tug designs and on the planned exploration and transportation missions."
The way forward for future EPS qualification has been paved. The engineering assessment has been performed based on the lessons learnt to update the subsystems requirements and providing insights into optimization of the future test campaigns. Several qualification approaches have been analysed demonstrating the time and budget savings the AQS could offer.
