Recent research at the University of Auckland has advanced the understanding of radio-frequency (RF) plasma generation and its interaction with magnetic field geometries for use in electric propulsion systems. Two PhD theses (Félicien Filleul, 2022 and Antonella Caldarelli, 2024) investigated the behaviour of low-temperature plasmas in linear devices equipped with variable magnetic fields, with particular emphasis on plasma expansion through magnetic nozzles.
Filleul’s thesis explored plasma transport in converging-diverging magnetic configurations, highlighting how magnetic field topology influences ionisation, confinement, and directed plasma flow. Caldarelli extended this work by examining the expansion of RF plasmas through various magnetic nozzle arrangements, including deflected fields that enable thrust vectoring. These studies used a range of diagnostic tools to measure ion energy, density, and flow directionality, providing new insights into the controllability and efficiency of plasma exhausts.
Several associated publications further developed this work. A 2021 paper in Physics of Plasmas described the construction and characterisation of a new experimental platform with tunable magnetic fields, enabling systematic studies of RF plasma behaviour. Subsequent conference and journal contributions analysed the effects of ion magnetisation on plasma generation and the spatial properties of ion beams in steered and symmetric nozzle geometries. One study demonstrated how magnetic field deflection can be used to manipulate ion beam direction, a key capability for propulsion systems requiring thrust vector control.
In a broader context, Balkenhohl et al. (2023) reviewed the development of low-power applied-field magnetoplasmadynamic (AF-MPD) thrusters. This review included efforts to refine performance models for such systems, providing a theoretical framework that complements the experimental work carried out in Auckland.
In parallel with these experimental and theoretical investigations, Dr Tianliang Zhang is leading a project to develop a novel thrust vector control (TVC) mechanism for electric propulsion systems based on a reconfigurable magnetic nozzle. Early experimental results suggest that precise beam steering can be achieved without compromising plasma performance, offering a promising pathway to more efficient and flexible electric propulsion systems.
References
Caldarelli, Antonella, “Radio-Frequency Plasma Expansion in Different Magnetic Nozzle Configurations”, PhD Thesis, The University of Auckland (2024)
Filleul, Félicien, “Radiofrequency Plasma Generation and Transport in Converging-Diverging Magnetic Fields”, PhD Thesis, The University of Auckland (2022), https://researchspace.auckland.ac.nz/handle/2292/64327
Balkenhohl, Jakob, et al. “A review of low-power applied-field magnetoplasmadynamic thruster research and the development of an improved performance model.” Journal of Electric Propulsion 2.1 (2023): 1.
Filleul, F., Caldarelli, A., Charles, C., Boswell, R., Rattenbury, N., & Cater, J. (2022, June). Ion magnetization effects on plasma generation in a magnetic nozzle RF device. In 37th International Electric Propulsion Conference. Electric Rocket Propulsion Society, Boston.
Filleul, F., Caldarelli, A., Charles, C., Boswell, R. W., Rattenbury, N., & Cater, J. (2021). Characterization of a new variable magnetic field linear plasma device. Physics of Plasmas, 28(12), 123514.
Caldarelli, A., Filleul, F., Charles, C., Rattenbury, N., & Cater, J. (2021). Preliminary measurements of a magnetic steering system for RF plasma thruster applications. In AIAA Propulsion and Energy 2021 Forum (p. 3401).
Caldarelli, A., Filleul, F., Charles, C., Boswell, R., Rattenbury, N., & Cater, J. (2022). Radial characterization of an ion beam in a deflected magnetic nozzle. Journal of Electric Propulsion, 1(1), 1-11.