Characterization of a 20 kW dual channel Hall thruster “TANDEM” with different propellants (Xe, Kr, and Ar)

A 20 kW class Hall Thruster, featuring two coaxial channels and a centrally mounted cathode, has been designed at the University of Pisa and manufactured by Aerospazio Tecnologie s.r.l. The thruster was preliminarily characterized in 2024 within the framework of the ESA TANDEM programme. The following paper outlines the findings from the recent characterization test campaign performed on the TANDEM thruster coupled with the new cathode developed within the CHEOPS-VHP-BB programme. This test was carried out at AEROSPAZIO Tecnologie in 2025 in the LVTF-3 test facility. The TANDEM thruster was operated with three different propellants (Xenon, Krypton, and Argon) at four operating points (from 4.5 to 20 kW) with discharge voltages of 300 and 400 V. An extended diagnostics activity was carried out including thrust measurements, plume diagnostics and temperature measurements. Thermal assessments were also performed using an infrared thermal camera. This document presents the experimental results collected throughout the testing. The experimental campaign showcased various operating regimes with transitions between them, and how they can affect TANDEM’s performance. The thruster was able to reach total specific impulses of over 2200 s during operation with Xenon and above 2300 s using Krypton. Efficiencies were between 50 and 55% with Xenon and up to 52% with Krypton. Efficiencies in Argon dropped to 30% or less. Margins for performance improvement exist and will be explored in future work. The project provided also promising results and relevant information for the development of new technology in terms of configurations, materials, thermal dissipation, and manufacturing processes.