Electric Propulsion Systems: from recent research developments to industrial space applications - STO-AVT-263
Monday 06 June 2016 - Friday 10 June 2016VKI secretariat, This email address is being protected from spambots. You need JavaScript enabled to view it.; Phone: +32 2 359 96 04
VKI Lecture Series STO-AVT- 263 on 6-7-8 June 2016
VKI Workshop on 9 -10 June 2016
Introduction
Copyright: ESA /AOES Medialab |
Today, 20% of active satellites (excluding classified ones) operate with electric propulsion systems. The advantages of this technology with respect to chemical propulsion is the high specific impulse that implies a significant saving in propellant mass, and the capability of a very good controllability due to the possibility of generating very low thrust and very small impulse bit. The STO-AVT-263 lecture series and related VKI workshop will provide a forum for discussion on electric propulsion systems. This activity has been tailored to provide professionals and students, from supporting industries, space agencies, and defense programs, the state-of-the-art in this rapidly progressing field of research. Prominent scientists have been invited to give lectures on their field of expertise. During the three-day STO lecture series and the first day of the VKI workshop, a course will address the current technological challenges in the field of electric propulsion, together with a review on relevant physico-chemical models and computational methods for engineering prediction, experimental facilities and measurement techniques, flight data, as well as disseminate information on ongoing and future projects associated with communication, scientific, and military satellites, and space exploration. A round table discussion on research perspectives will conclude the course. The last day of the VKI workshop, the participants will have the opportunity to present their research results through oral presentations and during a poster session, following a selection based on a review of submitted abstracts. The abstract for the workshop could be submitted during the registration process or be sent to the VKI library: This email address is being protected from spambots. You need JavaScript enabled to view it.. The deadline to submit an abstract is 27 May 2016. |
Programme AVT-263 and Workshop
STO-AVT-263 activity
VKI Lecture Series
Organizers: Thierry Magin (Von Karman Institute, Belgium) AND Jean-Luc Cambier (Air Force Research Laboratory, USA)
Monday 6 June 2016
- 08:00 Registration
- 09:00 Welcome address
Jean Muylaert, von Karman Institute for Fluid Dynamics, Belgium - 09:15 Trends in electric propulsion industry
Mariano Andrenucci, University of Pisa, Italy - 10:45 Coffee break
- 11:00 Role of electric propulsion in space missions
Davar Feili, ESA ESTEC, The Netherlands - 12:30 Lunch break
- 14:00 Fundamentals of electric propulsion systems
Dan Goebel, Jet Propulsion Laboratory, United States - 15:30 Coffee break
- 15:45 Ion engines and hollow cathodes: theory and modeling
Dan Goebel - 17:15 Welcome reception
Tuesday 7 June 2016
- 09:00 Physics and modeling of Hall effect thrusters
Jean-Pierre Boeuf, CNRS-LAPLACE, France - 10:30 Coffee break
- 10:45 Magnetoplasmadynamic thrusters, past, present, and future
Edgar Choueiri, Princeton University, United States - 12:15 Lunch break
- 14:00 Neutralizer-free ion propulsion
Dmytro Rafalskyi, Plasma Physics Laboratory, France - 15:30 Coffee break
- 15:45 Advanced electric propulsion concepts
James Polk, Jet Propulsion Laboratory, United States
Wednesday 8 June 2016
- 09:00 Electrostatic probe diagnostics for electric propulsion systems
Trevor Lafleur, Plasma Physics Laboratory, France - 10:30 Coffee break
- 10:45 Laser-aided diagnostics for electric propulsion systems
Stéphane Mazouffre, CNRS-ICARE, France - 12:15 Lunch break
- 13:15 Tour of the VKI experimental facilities
- 14:00 Capillary discharge thruster experiments and modeling
Robert Martin, Air Force Research Laboratory, United States - 15:30 Coffee break
- 15:45 Advanced diagnostics and thrusters: 3D Laser Induced Fluorescence and ECR thruster
Denis Packan, ONERA, France - 17:15 Closure of STO-AVT-263 activity
VKI Workshop
Organizers: Anne Bourdon (Plasma Physics Laboratory, France) and Thierry Magin (Von Karman Institute, belgium)
Thursday 9 June 2016
- 08:00 Registration
- 09:00 Welcome address
Anne Bourdon, Plasma Physics Laboratory, France - 09:15 Modeling of Magnetized low-temperature plasmas
Gerjan Hagelaar CNRS-LAPLACE, France - 10:45 Coffee break
- 11:00 Particle-in-Cell/Monte Carlo collisions simulations of plasma thrusters
Francesco Taccogna, CNR Bari, Italy - 12:30 Lunch break
- 14:00 Physics of magnetic nozzles for plasma thrusters and magnetically guided plasma plumes
Eduardo Ahedo, Universidad Carlos III de Madrid, Spain - 15:30 Coffee break
- 15:45 Round table discussion: Anne Bourdon, Eduardo Ahedo, Stephan Zurbach
Friday 10 June 2016
- 09:00 Theory for the anomalous electron transport in Hall-effect thrusters
Trevor Lafleur - 09:20 Revealing the electron anomalous transport in Hall-effect thruster
Francesco Taccogna - 09:40 2D Particle-in-cell simulations of the electron-cyclotron instability and
associated anomalous transport in Hall-effect thrusters
Vivien Croes, Plasma Physics Laboratory, France - 10:00 Low erosion concepts for Hall thrusters: magnetic shielding and wall less
configurations
Lou Grimaud, CNRS/ICARE, France - 10:20 Coffee break
- 10:40 Iodine as a propellant for ion thrusters
Pascaline Grondein, Plasma Physics Laboratory, France - 11:00 A performance model for RIT 3.5 and LEOSWEEP radio-frequency
gridded ion thrusters
Mantas Dobkevicius, University of Southampton, United Kingdom - 11:20 Hybrid PIC-fluid simulation of plasma thrusters and their plumes
Adrián Dominguez-Vazquez, Universidad Carlos III de Madrid, Spain - 11:40 COOLFluiD: an open source HPC platform for plasma simulation
Andrea Lani, von Karman Institute for Fluid Dynamics, Belgium - 12:00 The Kolesnikov effect in magnetized plasma flows
Thierry Magin, von Karman Institute for Fluid Dynamics, Belgium - 12:20 Closure of workshop & lunch
Workshop: list of abstracts
Theory for the anomalous electron transport in Hall-effect thrusters
T. Lafleur, S. Baalrud, and P. Chabert
Using insights from particle-in-cell (PIC) simulations, we develop a kinetic theory to explain the anomalous cross-field electron transport in Hall-effect thrusters (HETs). The large axial electric field in the acceleration region of HETs, together with the radially applied magnetic field, causes electrons to drift in the azimuthal direction with a very high velocity. This drives an electron cyclotron instability that produces large amplitude oscillations in the plasma density and azimuthal electric field, and which is convected downstream due to the large axial ion drift velocity. The frequency and wavelength of the instability are of the order of 5 MHz and 1 mm respectively, while the electric field amplitude can be of a similar magnitude to axial electric field itself. The instability leads to enhanced electron scattering many orders of magnitude higher than that from standard electron-neutral or electron-ion Coulomb collisions, and gives electron mobilities in good agreement with experiment. Since the instability is a strong function of almost all plasma properties, the mobility cannot in general be fitted with simple 1/B or 1/B2 scaling laws, and changes to the secondary electron emission coefficient of the HET channel walls are expected to play a role in the evolution of the instability.
Revealing the electron anomalous transport in Hall-effect thruster
F. Taccogna
The entire functioning principle of Hall-effect thruster (HET) is based on the electron transport in ExB field. It is well recognized that this discharge configuration creates high anisotropy and azimuthal fluctuations. In addition, the lateral surfaces play an active role due to the strong secondary electron emission in the acceleration region of the channel inducing space-charged saturated or even inverted sheaths. Both mechanisms, azimuthal fluctuations and electron-wall interaction, are responsible of the anomalous electron cross-field transport consisting in an axial electron current 10 times larger than the collision-induced current. Due to the low collisionality, both mechanisms have a strong kinetic character and any fluid treatment with an ad hoc fitting electron mobility is not helpful for understanding the real nature of electron transport. For this reason a fully kinetic 3D Particle-in-Cell / Monte Carlo Collision model of the HET channel discharge has been developed. The model has shown an interesting correlation between azimuthal, radial and axial dynamics. Azimuthal fluctuation characterized by λθ=3 mm develops due to electron cyclotron drift instability. It affects the electron distribution function determining an electron heating. A fast electron population increases the secondary electron emission that in turn induces a sheath collapse allowing a large flux of previously trapped electrons to hit the wall. These hot electrons induce more than one secondary on average, causing a net loss of electrons from the wall. This new situation damps the electron cyclotron drift instability and the azimuthal fluctuation disappears for a while before to develop again. The entire cycle takes about 0.2 μs.
2D Particle-in-cell simulations of the electron-cyclotron instability and associated anomalous transport in Hall-effect thrusters
V. Croes, T. Lafleur, Z. Bonaventura, F. Pechereau, A. Bourdon, P. Chabert
In this work we study the electron-cyclotron instability in Hall-effect thrusters (HETs) using a 2D electrostatic particle-in-cell (PIC) simulation. The simulation is configured with a Cartesian coordinate system where the magnetic field, *B0*, is aligned along the x-axis (*radial direction*, including absorbing walls), a constant applied electric field, *E0*, along the z-axis (perpendicular to the simulation plane), and the ExB direction along the y-axis (*Theta direction*, which uses periodic boundaries). Although electron transport can be well described by classical electron-neutral collision theory for low plasma densities, at sufficiently high densities (typical of those measured in HETs), a strong instability can be observed that enhances the electron mobility, even in the absence of electron-neutral collisions. The instability generates high frequency (of the order of MHz) and short wavelength (of the order of mm) fluctuations in both the electric field and charged particle densities, and we investigate the correlation between these fluctuations and the role they play in anomalous electron transport; work which compliments previous 1D simulations. Wall effects on the instability are studied here in the case where the plasma is self-consistently heated by the instability. Since the instability does not reach saturation in an infinitely long 2D system, saturation is achieved through the implementation of a finite axial length that models convection in the *E0* direction (i.e. perpendicular to the simulation plane).
Low erosion concepts for Hall thrusters: magnetic shielding and wall less configurations
L. Grimaud and S. Mazouffre
Hall thrusters (HT) are one of the most used electric propulsion system. They have become the system of choice for satellite station-keeping and, more recently, orbit transfer. The show-stopper for interplanetary mission is the relatively short lifespan that prevent their use in applications requiring multiple years of thrust time. The lifespan issue is even more pronounced when we turn to the emerging small satellite market which requires small, low power (300 W) thrusters. Kilowatt class HT are usually rated up to 10,000 hours while small hundreds watts one can typically only achieve a couple thousand hours of operation. The primary failure mode for Hall thrusters (HT) is dielectric channel erosion. The channel walls, usually made of a boron nitride compound, are in direct contact with the plasma and undergo heavy ion sputtering. This sputtering deforms the discharge channel geometry, which can change the dicharge characteristics over time. The erosion process eventually exposes the magnetic circuit of the thruster and causes it to fail. In this presentation we aim to present the erosion mechanism in Hall thrusters as well as two techniques to reduce erosion and increase lifespan in Hall thrusters. The first solution relies on an innovative magnetic topology called "magnetic shielding" discovered in 2011 at JPL. A quick summary of the theoretical basis for this configuration will be presented as well as some experimental results obtained with ICARE’s ISCT200-MS 200 W Hall thruster. Its performances are compared with the ISCT200-Mag, a thruster identical in size but with a standard magnetic topology. The other, more radical, solution is the Wall Less configuration. This configuration as been investigated at ICARE since 2014. This concept revolves around the idea of pushing the plasma outside the discharge channel and thus would get rid of the walls entirely. While the idea is still in its infancy several preliminary experimentations have already been conducted. Discharge characteristics will be presented for a series of modified thrusters.
Iodine as a propellant for ion thrusters
P. Grondein, T. Lafleur, P. Chabert and A. Aanesland
Most state-of-the-art electric space propulsion systems such as gridded and Hall thrusters use xenon as the propellant gas. However, xenon is rare, expensive to produce and used in a number of competing industrial applications. Alternatives to xenon are currently being investigated, and iodine has emerged as a potential candidate. Its lower cost, larger availability, its solid state at standard temperature and pressure, its low vapour pressure and its low ionization potential makes it an attractive option. A global model of iodine plasma inside an ion gridded thruster has therefore been developed to study behaviour and performances of this propellant. This global model allowed us to calculate plasma parameters such as neutral, ion and electron densities and electron temperature as well as system performances such as thrust, specific impulse and efficiencies. We compared the iodine results with ones obtained in xenon under otherwise similar conditions. When running with a neutral gas flow of 1 mg/s, an acceleration potential of 1000 V and RF power of 800 W, the model predicts a thrust of 30 mN for an extraction diameter of 60 mm for both iodine and xenon. The thruster efficiency is however 15% higher for iodine compared to xenon mainly due to the lower ionization energy for iodine and larger ion mass due to the contribution from I2 ions. Results of the iodine global model were compared with experimental data obtained under similar operating conditions and input parameters in a gridded ion thruster. An experimental test bench dedicated to iodine plasma study, inside a classic ion gridded thruster and PEGASES thruster, has been assembled with all precautions needed. Iodine is a corrosive gas and chemically active with certain metals (titanium, copper, silver, alloys of aluminium) and the right choice of materials is therefore important. At solid state at standard temperature and pressure, iodine is heated to sublimate, then injected inside the chamber where the neutral gas is ionized. The positive ion and electron densities obtained by the model and in experiments appeared to show close values, indicating that the iodine chemistry and reaction set used in the global model seem relevant to a first order approximation. A notable difference is observed for the negative density, which may be explained by the sensitivity of the Langmuir probe analysis used in this study.
This work has been done within the LABEX Plas@par project, and received financial state aid managed by the Agence Nationale de la Recherche, as part of the programme "Investissements d'avenir" under the reference ANR-11-IDEX-0004-02.
A Performance Model for RIT 3.5 and LEOSWEEP Radio-Frequency Gridded Ion Thrusters
M. Dobkevicius, M. Smirnova , A. Mingo
A comprehensive inductively coupled radio frequency (RF) ion thruster model was developed. The model consists of 0D plasma, 2D ion optics, 2D axis-symmetric electromagnetic (EM), 3D thermal and RF circuit sub-models. The ion optics sub-model uses the IBSIMU code to determine the ion beam properties. The 0D sub-model, constructed in Matlab, is used to determine volume-averaged plasma quantities such as density n0, conductivity σp and power loss Ploss by applying conservation of particles and energy equations. In the EM sub-model, the power losses due to eddy currents inside the thruster structure and power absorbed by plasma Pabs, represented by a complex conductivity σp, are obtained by solving the time–varying Maxwell’s equations for electric and magnetic fields using COMSOL multiphysics software. The power losses due to eddy currents inside the thruster’s structure, as well as the power fluxes from the plasma, as determined from the 0D model, toward the chamber and grid boundaries are used as heat sources in the 3D thermal sub-model constructed in COMSOL. Finally, the RF circuit sub-model designed in PSPICE is used to model the behaviour of the RF circuit and to determine losses inside the RF circuitry. Later, the data is used to analyse the matching and impedance transformation problem. The developed model was employed in designing and optimizing an RF gridded ion thruster for the LEOSWEEP (“Improving Low Earth Orbit Security with Enhanced Electric Propulsion”) mission. The mission aims to demonstrate the first active space debris removal of a Ukrainian rocket upper-stage using a contactless ion beam shepherd method. The model was also used to design a RIT 3.5 thruster for the NGGM (Next Generation Satellite Gravimetry Mission), and characterise its performance. During the presentation we aim to present the manner in which the developed model was used to design the thrusters. Additionally, we aim to show the thrusters’ performance and thermal behaviour as predicted by the model. Finally, we plan to discuss how well the model predicts the experimental RIT 3.5 thruster data.
Hybrid PIC-fluid simulation of plasma thrusters and their plumes
A. Dominguez-Vazquez, F. Cichocki, D. Pérez-Grande, M. Merino, P. Fajardo, E. Ahedo
Nowadays, current trends on electric propulsion proven technologies such as Ion Thrusters (IT) or Hall Effect Thrusters (HET) are focused on increasing the on board power (~20-100 kW), new control schemes (such as “direct drive”) or new mission scenarios. On the other hand, new thruster technologies, such as the Helicon PlasmaThruster (HPT) or the Electron-Cyclotron-Resonance Accelerator (ECRA), are strong candidates for future missions and are currently under development. In this context, the simulation of plasma thrusters and their plumes is becoming extremely important and demanding. Regarding the former, simulation tools are essential in order to reduce development time and costs, reveal optimization opportunities and predict operational parameters throughout the thrusters’ lifetime. As for the latter, the plume simulation enables the assessment of the plume interaction with sensitive S/C surfaces such as onboard sensors and solar panels. Besides, a refined plume expansion model is necessary in the design of active debris removal missions based on the ion beam shepherd technique, whose feasibility is currently being studied with a European Union funded project, named LEOSWEEP. In response to these needs, EP2 has decided to develop two new hybrid PIC-fluid codes: NOMADS (Non-structured Magnetically Aligned Discharge Simulator) for simulating the plasma physics of electric thrusters and their near plume and EP2-PLUS (Extensible Parallel Plasma PLUme Simulator) for simulating the far plume region. The former is an axisymmetric code based on the group’s broad expertise with previous simulation codes such as HallMA and HPHall2. NOMADS intends to be a new versatile simulation platform that extends the capabilities of previous codes and that will be applicable to thrusters sharing the commonalities of producing low density, low collisionality plasmas with strong magnetization of at least the electron population, thus including HET, HPT, ECRA and High-Efficiency Multistage Plasma Thruster (HEMPT). The latter is a 3D code dedicated to the simulation of rapidly-expanding plasma plumes into vacuum and their interaction with the spacecraft or a space debris object. Both codes benefit from a common code development methodology based on modularity, Test Driven Design philosophy, wide specific documentation and strict version control. Besides, in order to maximize code sharing and standardization, NOMADS and EP2-PLUS share the same overall architecture, data structure and interfaces, including common baseline modules and dedicated subroutines whenever possible. In both codes, heavy species (ions and neutrals) are moved with a conventional particle mover and collisions are simulated with dedicated Monte Carlo techniques. Dedicated population control algorithms will be developed in the future to improve the PIC statistics. On the electron side, NOMADS uses a Magnetic Field Aligned Mesh (MFAM) which leads to an important noise reduction and solves a reduced 12 moment approximation fluid model, based on Barakat and Shunk’s 16 moment approximation through a Cell-Centered Finite Volume Method. The electron population is modelled through bi-Maxwellian VDF, defined with two different electron temperatures in parallel and perpendicular directions to the magnetic field. Regarding EP2-PLUS, simplified electron closures (Boltzman, polytropic, numerical fittings from kinetic studies) are used to solve the unmagnetized and “dimly magnetized” plume cases.
COOLFluiD: an open source HPC platform for plasma simulation
A. Lani, A. A. Laguna, Y. Maneva, N. O. Munoz
COOLFluiD is a fully open source computational platform providing a collection of advanced multi-physics models and parallel solvers for flow/plasma simulations on unstructured grids. Special effort is devoted to the development of (1) thermo-chemical nonequilibrium solvers for re-entry aerothermodynamics, (2) single-fluid and multi-fluid MHD solvers for simulating magnetized plasmas, currently targeted towards space weather prediction. Of particular interest for possible space propulsion applications is the multi-fluid/Maxwell solver which is currently used for simulating collisional-to-collisionless solar plasmas (e.g. magnetic reconnection, wave propagation in the chromosphere) including the effects of chemistry and radiation. An overview of the current capabilities, most relevant results and perspectives of COOLFluiD developments for plasma simulations will be provided.
The Kolesnikov effect in magnetized plasma flows
T. Magin, J.B. Scoggins, Q. Wargnier, M. Massot
An accurate modeling of dissipative effects in plasmas is crucial to many applications. We have calculated the crossed contributions to the mass and energy transport fluxes coupling the electrons and heavy particles, such as atoms and ions, in multicomponent plasmas. This coupling effect was first introduced by Kolesnikov. To derive asymptotic solutions for multicomponent plasmas based on kinetic theory, it is essential to solve the distribution functions in the Enskog expansion up to second-order for electrons and up to first-order for heavy particles. However, the second-order electron transport fluxes should not be confused with Burnett fluxes. The heavy-particle diffusion velocities and heat flux are proportional to an average electron force expressed in terms of the electron diffusion driving force and temperature gradient. Conversely, the electron diffusion velocity and heat flux are proportional to the heavy-particle diffusion driving forces and temperature gradient. The magnetic field induces anisotropic transport fluxes when the electron collision frequency is lower than the electron cyclotron frequency of gyration around the magnetic lines. The explicit expressions for the transport coefficients are obtained by means of a Galerkin spectral method.
Fee & Registration
Early bird (before after April 6, 2016)
Normal Fee (after April 6, 2016)
For undergraduate student, the request to be considered for an award must accompany the application to attend the Lecture Series, and the applicant must provide a recommendation letter from his or her professor; if not done so, the request will not be taken into consideration. All possible alternative sources of funding should be investigated before aid is requested under this scheme, so that those most in need will benefit.
The fee includes printed notes, lunches, beverages, and administrative costs.
For non-Nato citizens, the participation to the three-day STO AVT 263 is pending an authorization to be requested directly to STO (STO Paris, attn : Mrs. S. Cheyne – AVT Panel, rue Ancelle 7, 92200 Neuilly-sur-Seine, France, or by e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it.) at least 6 weeks prior to this course. The acceptance should then be joined to your inscription and sent to VKI.
This lecture series AVT-STO-235 is opened to all NATO nation+ 22 EAPC/PARTNERSHIP for PEACE nations + 7 MEDITERRANEAN DIALOGUE nations.
METHOD OF PAYMENT
Payment 2 weeks prior to the beginning of the course (name and course title clearly indicated) by bank transfer to our account IBAN BE57 2100 3153 3035 , SWIFT BIC GEBABEBB
Location : von Karman Institute for Fluid Dynamics, Belgium