Measuring electron temperature temporal oscillations in an electrodeless thruster using floating harmonic probe techniques

Electrodeless thrusters are extensively studied these last years thanks to their capability to produce thrust without the need for external cathodes and the possibility to work with alternative propellants, therefore reducing erosion problems and costs. Within this family, the electron cyclotron resonance thruster has recently shown thrust efficiencies comparable to those of more mature technologies [1]. Nonetheless, questions are still open about the existence of oscillations and instabilities in the expanding plasma, and their possible relationship with cross-field plasma transport and plasma detachment, which are ultimately related to thruster efficiency. In this work, we investigate plasma instabilities by performing a first attempt to measure electron temperature oscillations in the plasma plume of the electron cyclotron thruster developed at ONERA using the novel floating harmonic probe technique [2]. Results will be compared to oscillations of electron density and emitted light from the plasma observed in our previous work [3].

[1] V. Désangles et al., J. Electr. Propuls., vol. 2, p. 10, 2023.

[2] B. J. Seo et al., Plasma Sources Sci. Technol., vol. 32, no. 7, p. 075012, 2023

[3] V. Desangles, F. Boni, and J. Jarrige, in Bulletin of the American Physical Society 76th Annual Gaseous Electronics Conference, 2023, p. HR2.00003.