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Poster Session II

4:30 pm – 6:30 pm, Wednesday October 15 Session DW5 COEX, Lobby E
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Tracing the origins of pulsed GHz emission in Hall Thrusters: from observed effects to underlying causes

Poster 75
Presenter: Freddy Gaboriau (LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 31062 Toulouse, France)
Authors: François Réot (LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 31062 Toulouse, France), Laurent Liard (LAPLACE, Université de Toulouse, CNRS, INPT, UPS, 31062 Toulouse, France), Valentin Mazières (DEOS group, ISAE-SUPAERO, 31055 Toulouse, France), Olivier Pascal (LAPLACE, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France), Vincent Laquerbe (Antenna Department, CNES, 31401Toulouse, France)



Plasma oscillations in Hall thrusters have been observed and studied at various spatial scales and frequency ranges. From low (kHz) to intermediate (MHz) frequencies, the physical phenomena  at their root have been relatively well understood, even though their intricacies and interconnection are yet to be fully ascertained. At  GHz frequencies, their physical origin has received, in the last decades, much less attention than their  lower-frequency counterparts. Yet, an accurate identification of the underlying processes and/or instabilities at play would contribute to the explanation of microwave radiation emitted from these thrusters, which is a threat to communication systems, as well as a better understanding of their overall physics. This work is devoted to the analysis of the GHz pulsed radiated emission in a similar experimental framework to that of Mazières et al. [1] One of its first and novel aspects consists in the gathering of a large number of pulses allowing for a statistical and pulse-to-pulse analysis, on a broad enough ]0, 4] GHz frequency band for their full spectral properties to be captured. A simultaneous temporal analysis of the low-frequency oscillations of the discharge completes the picture and  allows for  an eventual relationship between the two processes to be investigated. The results from this procedure uncovered the existence of such a relationship. [2] In particular, the pulses were shown to exhibit different spectral patterns depending on the phase of well-known kHz oscillations of the discharge current, such as Breathing Mode and Ion Transit Time Oscillations. Such a spectral dependence is expected to give valuable insights into the physical mechanisms at the root of this emission.

[1]   V. Mazières et al., Physics of Plasmas 29(7), 072107 (2022)

[2]   F. Réot et al., Physics of Plasma 32(2), 023509 (2025)

Funding acknowledgement

The authors acknowledge support from French space agency CNES and Agence Innovation Défense (AID).

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