Publications

2009

• PEGASES: Plasma Propulsion with Electronegative Gases
  
  • Leray Gary
  , 2009. The PEGASES thruster is a new plasma thruster concept. In a classical thruster, the thrust is produced by accelerating positive ions from an electron-positive ion plasma. In the PEGASES concept, an electronegative plasma is used, with electrons, positive and negative ions. Both positive and negative ions are used to create the thrust. Several advantages follow from this design. The PEGASES thruster can be divided into three stages: the ionization stage, the magnetic electron filtering stage, and the extraction and acceleration stage. In the first stage, the electronegative plasma is excited by a radiofrequency wave. In the second stage, electrons are spatially filtered to obtain an ion-ion plasma (electron free). In the third stage, both ion species are extracted and accelerated. This is made possible by the obtainment of an ion-ion plasma in the previous stage. The first two stages were investigated experimentally in the first PEGASES thruster prototype using electrostatic probes and retarding-field energy analyzers. The last two stages were investigated theoretically with fluid and kinetic models. With the results from all stages, a better understanding of the PEGASES concept stages was achieved. This allowed the design of the second PEGASES thruster prototype.
• Shell models and the possibility of application to fusion plasmas
  
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Garbet X.
  • Diamond P.H.
  , 2009.
• Gyrokinetic quasi-linear modelling of transport
  
  • Bourdelle C.
  • Casati A.
  • Imbeaux Frédéric
  • Garbet X.
  • Candy J.
  • Clairet F.
  • Gerbaud Thomas
  • Grandgirard V.
  • Gürcan Özgür D.
  • Hennequin Pascale
  • Sabot R.
  • Sarazin Y.
  • Vermare Laure
  • Waltz R. E.
  , 2009.
• Enhanced confinement with increased extent of the low magnetic shear region in tokamak plasmas
  
  • Nasi L.
  • Firpo Marie-Christine
  , 2009.
• Turbulence aux échelles électroniques dans le vent solaire
  
  • Sahraoui Fouad
  • Goldstein M. L.
  • Khotyaintsev Y. V.
  • Kiyani K. H.
  • Robert Patrick
  , 2009.
• Ion beam fluctuations in the wake of a plasma thruster
  
  • Pisarev V.
  • Tsikata Sedina
  • Honoré Cyrille
  • Lemoine N.
  • Grésillon D.
  , 2009.
• Etching of III-V semiconductors in inductively coupled chlorine plasmas
  
  • Despiau-Pujo Emilie
  , 2009. This thesis work is part of an emerging area of research: plasma etching for photonics and optoelectronics. The control of etching processes requires to predict the energies and fluxes of plasma species as function of the discharge parameters, and to understand the mechanisms of plasma-surface interaction. This work addresses both aspects through fluid modeling and atomistic simulations. We have developed molecular dynamics simulations to understand the fundamental mechanisms that govern the sputtering of two III-V semiconductors (GaAs and GaN) by low energy Ar ions. This numerical study, confronted to a series of experiments, shows that the composition of bombarded materials is modified over a few tens of angstroms and that sputtered Ga atoms leave the surface with energies sufficient to damage the etching sidewalls and passivation layers, in processes dominated by ion bombardment. We have also worked on fluid simulations (two-dimensional and global) to understand the dynamics of inductive chlorine discharges and to study the transport of species within the plasma bulk. Comparisons between model and experiments show that the 2D fluid model overestimates the charged particles densities but predicts fairly well the neutral and ionic composition of the plasma. The global model is the first step toward the modeling of the low power regime of inductive chlorine plasmas ; it has allowed us to study the instabilities that develop at the E to H transition.
• Generation of high pulsed magnetic field using a low inductance surface switch
  
  • Auvray Philippe
  • Larour Jean
  • Moustaizis Stavros
  , 2009. In experimental physics, a number of domains need the intense magnetization of a rather large volume, namely in condensed matter science. In laser-matter interaction and plasma science, the magnetic field may extend the interaction time of the charged particles. But the B-field values of interest, as predicted by analytical study or by numerical simulation, commonly overtake the 50-60T range, a limit for a reasonable capital investment. Moreover, the existing materials cannot withstand fields of 100T or more and some experiments are conducted in a semi-destructive mode, i.e. the coils explode radially, preserving the cell and the diagnostics. The single turn coil (STC) is an option for reaching such fields in a non-destructive pulsed mode. In order to study the generation of high energy particles for neutron production, we have have estimated that convenient operating conditions are a peak value of 50T in few cm3. Translated in current intensity, this objective is close to IMA with a rising time of 1 μs. To get such a very high current, we have built a low impedance transmission line connected to a massive brass STC with a 10 to 16mm bore. Two types of capacitor banks were used, based on 4.2-μF 50-kV low-inductance Haefely caps, charged under 30kV. The key component in the flat transmission line is a surface switch which has been described previously and can have an insertion inductance as low as few nH. In this switch, a number of channels are triggered along a melamina surface by an underlying conducting comb. Under the present conditions, when the channel number is 15 or more, a significant reduction of the inductance is observed (typ. 13 to 16nH for the whole circuit) and the peak current can reach 850kA, corresponding to 26 to 30T on axis. The field mapping, recorded with a mm axial resolution, is coherent with STC calculation. The paper will describe in detail the experimental setup, the associated probes, the calibration procedure and the results. We will conclude by presenting an alternative switch, currently under construction, able to increase the peak current, the reproducibility of B and the device lifetime. oral communication
• Small-scale density fluctuation modes in a Hall plasma thruster: experimental studies via collective light scattering
  
  • Tsikata Sedina
  • Lemoine N.
  • Honoré Cyrille
  • Grésillon D.
  • Pisarev V.
  , 2009.
• Structure of plasma sheet in the Martian magnetic tail. Simulations and Observations
  
  • Dubinin E.
  • Modolo Ronan
  • Chanteur Gérard
  • Fraenz M.
  , 2009, 4, pp.292.
• The IDIS Joint Research Activity: Tools for a Planetary Virtual Observatory
  
  • Chanteur Gérard
  , 2009, 4, pp.811. The IDIS Joint Research Activity (JRA-IDIS) of EuroPlaNet RI prepares essential tools implemented as web services allowing the Planetary Science community to interrogate some selected data centres, access and process data, and visualise the results. The key objectives of this JRA are: To define the data models and standards required to enable the services provided by SA IDIS to work in an interoperable fashion, and to investigate the basic elements of a future VO in planetology. To develop added value services to users that go beyond the provision of raw datasets, bringing the interrogation process much closer to the actual scientific aims of European planetary scientists. To generalise the experience gained from SkyBoT (Sky Body Tracker), a virtual observatory service for ephemeredes developed at Observatoire de Paris, to other datasets rovided by SA IDIS. To develop user-friendly interfaces to access to reference laboratory data required to interpret observations or to run simulation models whenever such data already exist. To create new databases, long-awaited by the scientific community, accessible through web services Products of JRA4 will be used by SA-IDIS or made available to all planetary scientists by SA-IDIS. Description of work JRA4 is broken down into four tasks. The first one is the coordination of the work package itself and its synchronization with the SA-IDIS, whilst tasks 2-4 will develop essential inputs for extending services provided to the community by the IDIS Service Activity (SA-IDIS). Task 1 - The two IDIS work packages SA-IDIS and JRA-IDIS are intrinsically linked, and will therefore be managed by a single coordinating team (CNRS/LPP, Palaiseau, and INAF/IASF, Rome) Task 2 - Interoperable Data Access is lead by CNRS/CESR, Toulouse, and by INAF/IASF, Rome. Task 2 will establish the basis allowing the evolution of SA-IDIS towards a future VO for planetary sciences. Meanwhile Task 2 will also provide a web-based general inventory of resources associated with a search engine. This inventory will allow user s to search resources based on general keywords. Such an approach is appropriate for interactive resource exploration, but will not fit the VO requirement (i.e. automated search up to the content of datasets). Task 3 - Added Value Services to Users is lead by DLR/IPR, and by the VO Data Centre of Paris Observatory. Task 3 will work in close conjunction with Task 2 to enable users to extract information from several data sets and compare them. It will develop interactive tools, which facilitate the retrieval of data sets for given regions, times, or data types. It will create interfaces for existing databases that currently have complex query and access procedures, making them widely accessible by the Planetary Science community. Task 4 - New databases is lead by CNRS/LPG and by DLR/IPR. Task 4 will develop a generic infrastructure of spectroscopic databases for solids (ices, minerals, organic molecules, extraterrestrial and synthetic organic matter). This infrastructure will be VO compliant and will enable the implementation of added value services as web services. A general presentation of the planned developments will be made.
• Europlanet RI/IDIS - Functions of the Technical Node
  
  • Schmidt Walter
  • Capria Maria Teresa
  • Chanteur Gérard
  , 2009, 4, pp.125. During the past four years the EuroPlaNet Integrated and Distributed Information System (IDIS) had developed into a functional prototype, which in the following years should grow into an effective support tool for all aspects of planetary sciences [1]. As planetary sciences encompass as diverse components as space exploration, ground- based observations, laboratory experiments and numerical modelling in several different scientific fields, it was decided early on in the project to divide the coordination responsibilities among different research institutes throughout Europe. The following thematic fields were selected, each associated with a specialized network node and its technical and scientific support staff as well as a group of experts in this field: Interiors and Surfaces of planets, Planetary Atmospheres, Space Plasma Sciences, Small Bodies and Dust in the Solar System and Planetary Dynamics. A sixth node,the Technical Node at the Finnish Meteorological Institute in Helsinki, serves as coordinator and default gateway of the network. The main purpose of the technical node is to provide the technical management and the coordination of the network, monitor its performance and support the integration of new services into the distribute d structure. It cooperates closely with the other Europlanet-RI activities which are partly set up to develop advanced services for the network like a multi-discipline data model, data mining services, virtual observatory functionality for many data sets related to planetary sciences etc. Additionally the technical node is coordi nating the access to such services which are not clearly related to any of the thematic nodes like aspects of instrument or mission development for planetary space missions, ground test facilities and laboratories for instrument verification and qualification, general network access tools etc. Staff from the technical node is also directly involved in several of the other Europlanet-RI activities to make the integration more efficient. Web access to IDIS via any of the mentioned nodes or e.g. the Technical Node at http://www.idis.europlanet-ri.eu
• IDIS Concept and scope
  
  • Capria Maria Teresa
  • Chanteur Gérard
  • Schmidt Walter
  , 2009, 4, pp.790.
• Scaling stellar jets to the laboratory: The power of simulations
  
  • Stehlé C.
  • Ciardi Andrea
  • Colombier Jean-Philippe
  • Gonzales M.
  • Lanz T.
  • Marocchino Alberto
  • Kozlova M.
  • Rus B.
  Laser and Particle Beams, Cambridge University Press (CUP), 2009, 27, pp.709-717. Advances in laser and Z-pinch technology, coupled with the development of plasma diagnostics, and the availability of high-performance computers, have recently stimulated the growth of high-energy density laboratory astrophysics. In particular, a number of experiments have been designed to study radiative shocks and jets with the aim of shedding new light on physical processes linked to the ejection and accretion of mass by newly born stars. Although general scaling laws are powerful tools to link laboratory experiments with astrophysical plasmas, the phenomena modeled are often too complicated for simple scaling to remain relevant. Nevertheless, the experiments can still give important insights into the physics of astrophysical systems and can be used to provide the basic experimental validation of numerical simulations in regimes of interest to astrophysics. We will illustrate the possible links between laboratory experiments, numerical simulations, and astrophysics in the context of stellar jets. First we will discuss the propagation of stellar jets in a cross-moving interstellar medium and the scaling to Z-pinch produced jets. Our second example focuses on slab-jets produced at the Prague Asterix Laser System laser installation and their practical applications to astrophysics. Finally, we illustrate the limitations of scaling for radiative shocks, which are found at the head of the most rapid stellar jets. (10.1017/S0263034609990449)
  DOI : 10.1017/S0263034609990449
• Influence of the electron cross-field diffusion in negative ion sources with the transverse magnetic field and the plasma-electrode bias
  
  • Bacal M.
  • Kuppel S.
  • Matsushita D.
  • Hatayama A.
  , 2010, 81 (2), pp.02B503. The physical mechanisms involved in the extraction of H- ions from the negative ion source are studied with a PIC 2D3V code. The effect of a weak magnetic field transverse to the extraction direction is taken into account, along with a variable bias voltage applied on the plasma electrode (PE). In addition to previous modeling works, the electron diffusion across the magnetic field is taken into account as a simple one-dimensional random-walk process. The results show that without PE bias, the value of the diffusion coefficient has a significant influence upon the value of the extracted H- current. However, the value of this coefficient does not affect qualitatively the mechanism leading to the peak of extracted H- ion current observed for an optimum value of the PE bias.
• Plasma Propulsion with Electronegative Gases
  
  • Aanesland Ane
  , 2009.
• Development of surface dielectric barrier discharge: electric field measurements
  
  • Allegraud Katia
  • Guaitella Olivier
  • Starikovskaia Svetlana
  • Rousseau Antoine
  , 2009.
• Nanosecond surface discharge at high pressures
  
  • Kosarev I.N.
  • Sagulenko P.N.
  • Khorunzhenko V.I.
  • Starikovskaia Svetlana
  , 2009.
• Numerical simulation of plasma-assisted ignition in CH4:air mixtures
  
  • Aleksandrov N.L.
  • Kindysheva S.V.
  • Kukaev E.N.
  • Starikovskaia Svetlana
  • Starikovskii A.Yu.
  , 2009.
• Structure of a MHCD in the normal regime in pure argon
  
  • Lazzaroni Claudia
  • Chabert Pascal
  • Rousseau Antoine
  • Sadeghi N.
  , 2009.
• Heat and Particle Transport Experiments in Tore Supra and HL-2A with ECRH and SMBI
  
  • Zou X. L.
  • Song S.
  • Giruzzi G.
  • Garbet X.
  • Honoré Cyrille
  • Ségui J.-L.
  • Elbeze D.
  • Clairet F.
  • Sabot R.
  • Bucalossi J.
  • Hennequin Pascale
  • Lenholm M.
  • Magne R.
  • Tore Supra Team
  , 2009, ECA Vol. 33E (P-4.210).
• On plasma rotation in tokamaks with toroidal magnetic field ripple and no external momentum input
  
  • Fenzi C.
  • Trier Elisée
  • Hennequin Pascale
  • Garbet X.
  • Bourdelle C.
  • Aniel T.
  • Clairet F.
  • Gil C.
  • Gürcan Özgür D.
  • Imbeaux Frédéric
  • Sabot R.
  • Tore Supra Team
  , 2009.
• A first comparison between probes, fast imaging, and reflectometry synchronous measurements of edge turbulence in Tore Supra
  
  • Brochard F.
  • Fedorczak N.
  • Bonhomme Gildas
  • Clairet F.
  • Farge M.
  • Ghendrih Ph.
  • Gunn J.
  • Hennequin Pascale
  • Heuraux S.
  • Lemoine N.
  • Monier-Garbet P.
  • Nguyen R.
  • Oldenburger S.
  • Vermare Laure
  , 2009, ECA Vol. 33E (O-2.006). Oral
• Turbulence in Tore Supra plasmas: measurements and validation of nonlinear simulations
  
  • Casati A.
  • Gerbaud T.
  • Hennequin Pascale
  • Bourdelle C.
  • Candy J.
  • Clairet F.
  • Garbet X.
  • Grandgirard V.
  • Gürcan Özgür D.
  • Heuraux S.
  • Hoang G.T.
  • Honoré Cyrille
  • Imbeaux Frédéric
  • Sabot R.
  • Sarazin Y.
  • Vermare Laure
  • Waltz R. E.
  , 2009, ECA Vol.33E (O-4.040). Oral
• Scaling of Turbulence and Transport on Tore Supra with dimensionless parameters rho* and nu
  
  • Vermare Laure
  • Bourdelle C.
  • Hennequin Pascale
  • Artaud J.F.
  • Basiuk V.
  • Clairet F.
  • Devynck P.
  • Falchetto G.
  • Fenzi C.
  • Imbeaux Frédéric
  • Monier-Garbet P.
  • Gürcan Özgür D.
  • Sabot R.
  • Schubert M.
  • Ségui J.-L.
  • Tore Supra Team
  , 2009, ECA Vol.33E (P-4.208).