With the large number of satellites and the militarization of orbits, space surveillance is becoming essential. For example, in 2009, the European Space Agency (ESA) created the Space Situational Awareness (SSA) program, which aims to maintain independent access for Europe to space and its use through space surveillance. Among the stated requirements is the ability to identify satellites in orbit and detect any hostile maneuvers in space.

Today, satellites are increasingly equipped with electric propulsion systems. These systems enable the satellite to be maneuvered by ejecting ions at very high speed, which, after electronic neutralization, form a plasma plume of varying sizes at the thruster outlet. The presence of this plasma could enable the development of satellite maneuver detection systems.

A first approach could consist of obtaining information from a passive detection system that exploits the RF emissions produced by plasma thrusters during operation. Indeed, it has been shown that these thrusters generate emissions whose spectral content and physical origin remain to be clarified before such a detection system can be designed [1,2].

Another way to detect the operation of a plasma thruster could be to use an active detection system such as radar. In this specific case, it is necessary to know the radar cross section (RCS) of the plasma plume, which is a complex parameter that depends on the frequency, polarization, and direction of arrival of the incident wave generated by the radar, and possibly the position of the radar receiver in the case of a bistatic system. However, the RCS of an object, even a relatively simple one, is difficult to evaluate and is generally obtained by numerical simulation or experimental characterization. In the case of the plasma plume, many problems arise.

First, the plasma plume is a complex medium, frequency-dispersive, and inhomogeneous. Its properties depend on the type of thruster and its mode of operation. Furthermore, in order to operate it on Earth, it must be placed in an ultra-high vacuum chamber, usually made of metal, to meet the mechanical constraints of pressure differences. Obtaining accurate electromagnetic measurements in such a reverberant environment remains a challenge.

In this PhD work, we propose to first estimate the RCS of a plasma plume numerically using a multi-physics simulation method previously developed as part of Naomi de Mejanes' PhD work [3]. In addition to this work, we plan to develop advanced processing techniques for RCS measurement in reverberant environments [4]. These methods will be used to measure the RCS of plasmas and compare it with the results from the numerical simulation of the problem under test.

To do so, the PhD work will be organized as follows:

- Literature review on the RCS of plasmas and on methods for measuring RCS in reverberant environments (e.g., reverberation chambers).

- Numerical electromagnetic study with a multi-physics numerical simulation tool [3] of the RCS of platforms including a thruster plume model, as well as a test case involving a low-pressure plasma reactor simulating the plume of a thruster for reference [5]. 

- Development of advanced signal processing methods for extracting RCS in reverberant environments.

- RCS measurements of the test case in an anechoic environment for reference.

- RCS measurements of the test case in a reverberant environment using the developed methods and comparison with reference measurements in an anechoic chamber.

This work will be supervised by ISAE-SUPAERO, GeePs, and LAPLACE. In the end, this should enable us to acquire the skills and maturity necessary to numerically and experimentally characterize the RCS of the plasma plume of an electric space propulsion system. In addition, the results of this PhD work could also provide useful information for eventually addressing the opposite problem, namely improving the stealth of a target by generating plasmas around it.

[1] V. Mazières et al., “Broadband (kHz−GHz) characterization of instabilities in Hall thruster inside a metallic vacuum chamber”, Phys. Plasmas, vol. 29, no. 7, Jul. 2022.

[2] F. Réot et al., “Spectral dependency of pulsed GHz electromagnetic emission from Hall thrusters on discharge current oscillations”, Phys. Plasmas, vol. 32, no. 2, Feb. 2025.

[3] N. de Mejanes et al., “Simulation of the microwave propagation through the plume of a Hall thruster integrated on small spacecraft”, J. Appl. Phys., vol. 131, no. 24, Jun. 2022. 

[4] A. Reis et al., “Radar cross section pattern measurements in a mode-stirred reverberation chamber: Theory and experiments”, IEEE Trans. Antennas Propag., vol. 69, no. 9, Sep. 2021.

[5] O. Pascal et al., “Mimicking electric thruster plumes on earth to measure the radiation patterns of CubeSat antennas”, 2025 ESA Workshop on Aerospace EMC, May 2025.

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For more Information about the topics and the co-financial partner (found by the lab !); contact Directeur de thèse -romain.pascaud@isae-supaero.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time !