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Accueil du site > Installations expérimentales > Propulsion spatiale & souffleries hypersoniques

Propulsion spatiale & souffleries hypersoniques

Ground-based facilities for investigations in the field of Electric Propulsion.

The ICARE institute owns two unique and completing ground-based test benches for fundamental investigations as well as applied studies in the field of electric propulsion. The basic need is here to reproduce the space environment a satellite or a spacecraft experiences far above the Earth atmosphere in terms of particle density on the one hand and boundary conditions on the other hand. These specific constraints necessitate to warrant a very low residual gas pressure level and to operate in a large vacuum chamber. The density of particles, in the form of molecules, atoms and ions, in the tank must be such that the collision mean free path is below any characteristic dimension of the system (e.g. the tank radius) to avoid artificially modifying the discharge and ion beam properties. Besides, the level of contaminants like hydrogen, water and organic compounds must be as low as possible and real-time monitored with a mass spectrometer. A tank with long sizes allows to diminish wall effects. For instance, the sputtering yield of walls and components inside the tank due to bombardment by high energy ions must be limited by reducing particle fluxes per unit area and by placing carbon-made screens.

PIVOINE-2g The PIVOINE-2G facility consists of a large cylindrical chamber (4m × 2m) equipped with a high-capacity cryogenic pumping system able to maintain a pressure of 10-5 mbar for a large gas flow and a large thermal load. The cryosurface temperature is presently optimized for pumping xenon, the current propellant of electric thruster. The operation margin of the cryogenic heads permits to go down in temperature, hence the possibility to pump krypton and argon as well but with a lower efficiency. The bench is equipped with many diagnostic tools and measuring devices like a thrust balance and ion current probes.
Among many high-quality R&D activities carried out by researchers and engineers in the PIVOINE-2g bench we can cite as an example the development and test of the Snecma-built PPS®1350-G Hall thrusters that propelled the Smart 1 scientific probe from the ESA during its 15-month trip to the Moon.

NExET The NExET facility, which was first operates in 2009, is a relatively small cylindrical tank (1.8m × 0.8m) with a cryopump especially designed for SF6, an electronegative gas used as propellant for the ion-ion plasma-based PEGASES thruster. The cryosurface temperature allows, however, to also pump noble gas like xenon and krypton. This chamber serves to test and investigate low-power thrusters and ion sources of various types. Besides, it is of a great interest for the development and adjust of efficient tools for diagnosing plasma media and fast ion beams.

The NExET and PIVOINE-2G facilities form a complementary set of high-performance instruments and they make the ICARE laboratory a key actor in the electric propulsion area.

The Plateform FAST :’Facilities for Aerothermodynamics & Supersonic Technologies’

The study of the aerothermodynamic physics is one of the focus of the Icare’s reserches. Three supersonic /hypersonic wind tunnels are dedicated to the simulation of some properties that take place during flight at hypersonic speed of a spacecraft. Indeed, upon the atmospheric entry, the supersonic/hypersonic vehicle passes through layers with different gas density : for altitudes above 120 km, the flow regime corresponds to a free molecular regime, where the collision frequency is very low. The flow is then governed by the Boltzmann equation without the collision term. Such a regime is characterized by a number of Kudsen >10 and a Reynolds number < 1. Between 100 and 120 km of altitude the flow can be modeled by the kinetic gases theory, characterized by a number of Kudsen ranged between 0.1 and 10. The Monte Carlo method is applied for the numerical simulations making up the bridge of the gap between the molecular theory and Navier Stokes equations. Between 80 and 100 km of altitude, the Kudsen number decreases and the collision frequency increases. The Navier Stokes equations describing the continuum can then be applied except in areas with high gradient, so close to the wall, where the shock layer become strongly dissipative. At last, below 80 km, the collision frequency becomes very high, the shock waves become very strong and the real gas effects appear due to high thermal and chemical activity.

MARHY is a wind tunnel for aerodynamic studies for hypersonic/supersonic rarefied flows. In this low density facility (diameter 2 m length 5 m) an adapted nozzle provides a stationary flow with a Mach number in th range 0.8 to 21 with a pumping system of 2 prymary pumps, 2 intermediary Root and 12 roots pumping 156 000 m3/h. For a Mach number of 20 n, the Reynolds number is 835 and the velocity 1500m/s. In this facility the interactions of the low temperature –rarefied flow (1-10 Pa) with a model (heat flux, flow near the surafce, stregnth, plasma flow control) are studied for space applications. The performance of Marhy are unique in Europe due to the large range of Mach and Reynolds numbers obtained in continuos running conditions.

EDITH, is a supersonic/hypersonic wind–tunnel operating at high Reynolds numbers. The studies concerns as well as fundamental research of shock waves, hysteresis effects between Mach and regular reflections, and is well suited for studying phenomena like laminar –turbulent transitions which take place in the boundary layers formed at high velocities.

PHEDRA is a plasma ground test facility used to simulate low pressure flight conditions in the upper layer of the planetary atmospheres. An arc-jet generator operates in a cylindrical chamber of 1 ;1 m in diameter and 4.3 m length, pumped with 3 primary pumps and 3 Roots pumps, which capacity (27 000 m3/h) insures a residual pressure ranged between 1 to 100 Pa. Different working gases can be used like Argon , nitrogen, CO2, CH4 Air, allowing the simulation of several planetary entry conditions like earth (80%N2-20%O2), Mars (97%CO2-3%N2) or Titan (99% N2-1% CH4). The advantages of the home-made designed plasma source can be found in the stability of the plasma flow, the high specific enthalpy, up to 50 MJ/kg due to the low mass flow rate and the low rate of contamination which could provides from the erosion of the cathode.

These low pressure facilities are complementary and allow the study of different aspects of the spacecraft entry : aerodynamics, strength, heat flux, plasma radiative effects, ionization, gas/surface interactions, and non equilibrium processes. In this purpose, various measurement techniques have been developed and adapted to each experimental conditions like optical spectrometry (VUV- visible and IR), electrostatic probes, Pitot probes, infrared thermography, heat flux probes, aerodynamic balances Schlieren visualization, and standard pressure and temperature measurements.