Probing the physics of ion thrusters with coherent light

30 june 2021. 13.00 CEST

On site: Salón de actos (Leganés) / Online:

Prof. Stéphane Mazouffre  from CNRS, ICARE laboratory, Orléans, France

Ion Thrusters (ITs), also termed electric or plasma thrusters, are efficient ion accelerators used to propel satellites and space probes. Contrary to chemical thrusters, ion thrusters eject the propellant at very high speed, which directly translates into a low propellant mass consumption for a given maneuver or mission. ITs therefore allow either a drastic decrease of the spacecraft mass or the expansion of the vehicle capabilities. There is a wide variety of IT technologies that cover a broad range of missions and maneuvers, all devices nevertheless rest upon a low-pressure plasma discharge. Even though the technological development of electric propulsion started more than half a century ago, physical processes that govern the plasma discharge and the beam of ITs, and in fine performances, are complex and still ill-understood. As a consequence, optimization of existing devices and development of new architectures remain very empirical, hence lengthy and expensive. A better understanding of phenomena such as electron transport, turbulence and plasma-wall interactions requires comparisons between numerical simulation outcomes and experimental data about neutrals, electron and ion properties and dynamics.

In this contribution, we will examine the relevance and the advantages in employing laser-aided diagnostics, i.e. coherent rays of light, to probe the discharge and the beam of ITs. Two types of laser technique will be presented along with experimental results, namely: Laser-Induced Fluorescence (LIF) spectroscopy and Incoherent Thomson Scattering (ITS). LIF allows among other things measurement of the atom and ion velocity distribution from which particle temperature and mean velocity can be extracted. ITS gives access to the electron energy distribution function, a very fundamental quantity in low-temperature low-pressure plasmas.

Stéphane Mazouffre

Stéphane Mazouffre is a Research Director at the French National Research Center (CNRS).

After graduating from the ENSIL and the University of Limoges, France, in material science and plasma physics in 1996, he received a PhD in the field of low-temperature plasma physics in 2001 from the Eindhoven University of Technology (TU/e), The Netherlands. His research activities in spacecraft electric propulsion began in 2003 after he joined the ICARE laboratory in Orléans, France. He is currently the head of the Electric Propulsion Team at ICARE. He is also the director of the ORACLE joint-laboratory between ICARE and the Exotrail startup.

His research interests cover Hall thrusters and variants, new electric propulsion concepts and micropropulsion. His research also extends to the physics and technology of hollow cathodes and the physics of magnetized discharges. He is especially recognized for the development of laser diagnostics. He has authored over 110 scientific publications and more than 130 conference papers.

Dr. Mazouffre was a recipient of the Bronze Medal of the CNRS in 2008 and of the Noah Hershkowitz Award of the Institute of Physics in 2012. He is a senior member of the American Institute of Aeronautics and Astronautics and a member of the BoD of the Electric Rocket Propulsion Society. In 2020 he was awarded a Chair of Excellence from the Carlos III University in Madrid to work on laser spectroscopy for propulsion.