Superconductor-Based Readiness Enhanced Magnetoplasmadynamic Electric Propulsion

Project Information

SUPREME

Grant agreement ID: 101113107

DOI

10.3030/101113107

Project closed

EC signature date 17 April 2023

Start date 1 June 2023

End date 30 November 2025

Funded under

• The European Innovation Council (EIC)

Total cost

€ 2 499 995,75

EU contribution

€ 2 499 995,75

Coordinated by

UNIVERSITY OF STUTTGART
Germany

Periodic Reporting for period 1 - SUPREME (Superconductor-Based Readiness Enhanced Magnetoplasmadynamic Electric Propulsion)

Reporting period: 2023-06-01 to 2024-05-31

Summary of the context and overall objectives of the project

The next revolution in space will be driven by high-power electric propulsion (EP) technology. SUPREME aims to lead this revolution within EP, essential for sustainable progress in areas like On-Orbit Servicing, Assembly, and Manufacture (OSAM), in-space cloud computing, and space debris mitigation. However, current EP technologies face challenges in cost-effectiveness, sustainability, and performance as well as performance variability at high power levels. In Electric Propulsion technology, steady state AF-MPD thrusters are known for their efficiency, throttle-ability, propellant flexibility and scalability. and remarkable thrust levels. Research into their development has been ongoing since the 1960s. However, AF-MPD technology remained at low TRL due to challenges in thruster lifetime and flight readiness posed by conventional magnets. Through the adoption of High-Temperature Superconductors (HTS), the limitation of conventional electromagnets can be mitigated, and for thruster lifetime we have developed the new and better multi-channel hollow cathodes. Leveraging HTS coils enables AF-MPD to achieve the necessary high magnetic fields in a compact and lightweight system, thus advancing it towards flight feasibility. A radiatively cooled anode, eliminating active cooling, completes the image.

The SUPREME approach represents a significant milestone in European space technology by aiming to develop the first prototype EP system incorporating High-Temperature Superconductors (HTS). Building upon the advancements of the EU MEESST project, which successfully utilizes HTS coils for S/C re-entry shielding, SUPREME seeks to integrate HTS into AF-MPD thrusters. By developing, manufacturing, and testing a 5 kW AF-MPD thruster, SUPREME aims to showcase the integration of HTS coils. Additionally, the project will pioneer the development of a customized Power Processing Unit (PPU) for AF-MPD discharges, leveraging flight-qualified HET PPUs.

The method follows a structured space system development approach, aimed at advancing the prototype's design while effectively tracking progress through key milestones, staring with an initial system requirements study to establish a common baseline, followed by detailed design work on the AFM, a novel element and by integration of HTS coil technology. These concurrent activities are geared towards a unified CDR and SRR for final prototype validation before integration and testing.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

A successful internal PDR was conducted in Dec. 2023, where preliminary designs for all subsystems were presented. Reports for the PDR, a Requirements Review, and a Review of the Test Program to reach TRL5 were generated and uploaded to the EU portal. The CDR is planned for Sept. 2024 with the intent of freezing designs and start manufacturing and assembly.

A method has been developed to scale the 100 kW thruster IRS AF-MPD T SX3 down to the power of SUPREME of 5 kW. USTUTT's SX3 was used as one of the most successful AF-MPDTs in terms of operational features and high thrust efficiencies. This approach also lead to a magnetic field configuration for SUPREME that is geometrically similar to the one of SX3, which is considered a verifying element. The thermal analysis approved the design, confirming that the thruster can be operated almost continuously. A further element is the LaB6 cathode. The current design mitigates the life time issues that usual cathodes have. This cathode is designed, manufacturing is engaged. A new USTUTT facility to test hollow cathodes has been commissioned and set in operation. OES and thermo-structural characterization are possible. The output will functionally qualify the cathode and also serve for optimization campaigns. In contrast to the large SUPREME facility, it allows for specific characterisation and ad hoc investigations. This is a strong risk mitigation, as the SUPREME facility is accompanied by a high system complexity, and the time constraints of SUPREME in combination with the facility needs yield long test times. A modernization of the IRS facility for SUPREME was performed, implementing aspects such as automation of the evacuation process, modernization of the control systems, and vacuum quality optimization via implementation of a temperature control for the pump oil. A high precision thrust balance has been designed. This has benefited from the thruster scaling and analyses, where the expected thrust values have been used to enable sensor selection but also for balance design. An adaptation of chamber flange systems for interfaces has been established.

Interaction with CRISA, PEAK and UT to design PPU, PSU and HTSC systems for the test are highly entangled. The PPU, e.g. needed current and voltage levels and interface information to the facility. The HTSC interferes with geometries in the facility and a potential "thermal management" to control the maximum allowable temperature along copper routing and coil. Here, a trade has been made between the pressure level in the facility and thermal insulation needed. The aforementioned entanglement was a very important activity for the entire team, as only the combination of the know-how and the respective analysis tools made available by the different partners, making use of the previously developed requirements, allowed the development of the preliminary HTSC system for the test set-up, a preliminary PPU and PSU, hollow cathode, and thruster. A preliminary PPU has been established by Airbus Crisa based on the requirements settled by WP 2. PEAK has assessed information concerning relevant propellant feeding systems.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The R&D for thruster, HTSC system, and test setup is pushing the limits of current thruster and test technology. Correspondingly, demonstrating the operation of SUPREME will extend these limits significantly. The beyond the state of the art status is derived from the synopsis of elements such as HTSC, cathode, TMS, radiatively cooled anode, PSU, and PPU for two reasons: Firstly, these systems enable flight capability, secondly, the team's infrastructure is more or less a ticket to implement these technologies.
Results with a post PDR thruster design showed promising outcomes in terms of the thermo-structural behavior. This is a breakthrough as it approves SUPREME to be run in steady state. At the same time, the facility parameters in conjunction with the cryogenic system design (UT) confirm the feasibility of the cryo-system and the HTS coil employing MLI for the tests of SUPREME. This capability is be world-unique. Other entities (Japan, NZ, China, Russia) have tested w/o TMS, thus being able to test their systems only for short periods of time. Therefore, thruster and cathode cannot get to steady state leading to non-representative operation. The same applies to the erosion rates of the cathodes, an aspect that corresponds with limited life time.

SUPREME system at a glance

Newly refurbished facility. Top view, lid open.

SUPREME Test facility; view onto the tank lid

Hollow Cathode Test Facility (new) with "dummy" cathode in operation.

Newly refurbished facility. Side view, lid open.

AF-MPD SX3 in operation on argon at the IRS.