Characterisation of the 20 kW TANDEM Hall Thruster Cathode and 3D-printed Anodes in the Framework of the CHEOPS-VHP-BB Project

Future large telecommunication platforms, cargo tugs, and exploration stages will require very high power electric propulsion, making it essential for Europe to consolidate sovereign capability in the 10–25 kW Hall class. This paper reports the development and testing of two CHEOPS-VHP-BB building blocks on the 20 kW dual-channel TANDEM thruster: an upgraded high-current hollow cathode and additively manufactured anode distributors. The work combines the University of Pisa’s design capabilities with Aerospazio’s testing expertise, large vacuum facilities, and advanced diagnostics. The anodes were designed for additive manufacturing with the aid of free-molecular-flow modelling, produced by laser powder bed fusion in stainless steel, assessed for azimuthal uniformity with custom Aerospazio instrumentation, and full-scale fired on TANDEM in Xe, Kr, and Ar. The cathode was designed using thermo-mechanical simulations, fabricated in three identical models, and characterised through thermal, ignition, and diode-mode sweeps from 10 to 100 A on all three propellants. One unit completed full performance characterisation, while a 1,000 h argon endurance run and environmental tests (TVAC, shock, vibration) are ongoing. The other units were integrated and tested on TANDEM and are scheduled for tests with Safran’s PPS®20k. Results demonstrate the first publicly reported 3D-printed anode installed and fired on a 20 kW-class Hall thruster, achieving azimuthal uniformity within ∼10%. The cathode operated stably across all propellants with low discharge voltage and RMS current oscillations, and has been successfully demonstrated on TANDEM. These results enhance Aerospazio’s test capabilities and validate UniPi’s design approach, supporting a credible path to TRL 6 for rapid European adoption of very high power electric propulsion.