Publications

2012

• Low jitter, high current spark gap operating with air at normal pressure
  
  • Arantchouk Léonid
  • Houard Aurélien
  • Brelet Yohann
  • Forestier Benjamin
  • Carbonnel Jérôme
  • Larour Jean
  • Mysyrowicz André
  , 2012, pp.250. oral presentation. We demonstrate a simple, reliable air spark gap operating at atmospheric pressure and able to switch currents in excess of 10 kA. The spark gap with an interelectrode spacing close to10 mm is remotely triggered by a femtosecond laser system. This laser delivers pulses at 800 nm of typically 350 fs duration and energy of 200-250 mJ, corresponding to a peak power of about 600 GW. After propagation in air, the weakly converging laser beam undergoes filamentation. This leads to the production of a 1-2 m long continuous plasma column of nearly uniform longitudinal electron density n ~ 1016 electrons/cm3. The plasma column of diameter ~ 5 mm connects quasi instantaneously to electrodes. We studied two switch configurations. In first one two cylindrical electrodes of diameter 36 mm pulse charged up to 0.6-1.2 of the self-break voltage (25-30 kV). The triggered laser beam passes through holes 3 and 5 mm diameter. A sub-nanosecond jitter is demonstrated. The second configuration consists of spherical metal electrodes of 10 and 20-mm diameter DC-charged. They are connected to the laser produced plasma channel by grazing contact with vertical electrode shift of 2-3 mm. Jitter of 1-3 ns have been measured here.
• Study of GAMs on Tore Supra using Doppler backscattering
  
  • Vermare Laure
  • Hennequin Pascale
  • Gürcan Özgür D.
  • Storelli A.
  , 2012, oral.
• New regime of small scale density fluctuations in presence of electron heating in Tore Supra
  
  • Hennequin Pascale
  • Vermare Laure
  • Gürcan Özgür D.
  • Morel Pierre
  • Storelli A.
  • Bourdelle C.
  • Dumont R.
  • Tore Supra Team
  , 2012.
• Is "near edge" transport non-local?
  
  • Gürcan Özgür D.
  • Vermare Laure
  • Hennequin Pascale
  • Berionni Vincent
  • Diamond P.H.
  • Dif-Pradelier G.
  • Garbet X.
  • Ghendrih Ph.
  • Grandgirard V.
  • Mcdevitt C.J.
  • Morel Pierre
  • Sarazin Y.
  • Storelli A.
  • Bourdelle C.
  • Tore Supra Team
  , 2012, oral.
• RF driven rotation in Tore Supra
  
  • Fenzi C.
  • Chouli B.
  • Dumont R.
  • Elbeze D.
  • Guimaraes-Filho Z.
  • Hennequin Pascale
  • Lotte P.
  • Maget P.
  • Tore Supra Team
  , 2012.
• Dependence of properties of Geodesic Acoustic Modes (GAM) on SOL and edge flows in Tore Supra
  
  • Storelli A.
  • Hennequin Pascale
  • Gürcan Özgür D.
  • Vermare Laure
  • Tore Supra Team
  , 2012.
• Effects due to adsorbed atoms upon angular and energy distributions of surface produced negative hydrogen ions
  
  • Wada M.
  • Bacal M.
  • Kasuya T.
  • Kato S.
  • Kenmotsu T.
  • Sasao M.
  , 2013, 1515, pp.59-65. Exposure to Cs added hydrogen discharge makes surface of plasma grid of a negative hydrogen ion source covered with Cs and hydrogen. A Monte-Carlo particle simulation code ACAT was run to evaluate the effects due to adsorbed Cs and H atoms upon the angular and energy distributions of H atoms leaving the surface. Accumulation of H atoms on the surface reduces particle reflection coefficients and the mean energy of backscattered H atoms. Angular distributions of H atoms reflected from the hydrogen covered surface tend to be under-cosine at lower energies. Desorption of adsorbed H atoms is more efficient for hydrogen positive ions than for Cs positive ions at lower incident energy. At higher energy more than 100 eV, Cs ions desorb adsorbed H atoms more efficiently than hydrogen ions.
• Negative ion production by plasma-surface interaction in caesiated negative ion sources
  
  • Bacal M.
  • Wada M.
  , 2013, 1515, pp.41-48. The purpose of the present work is to provide a method for calculating the negative hydrogen ion yield due to fast and thermal ions and atoms versus the surface work function. The value of the decay factor in Rassers equation is re-examined, to make possible the use of this equation to this aim. The analysis of the data from two experiments lead to two different values for the decay factor. The lower value, 2.13×10−5 eV s/m, allows to determine the yield of backscattered negative ions. The higher value, 6.4×10−5 eV s/m, leads to the total yield. The fractions of the negative ions produced by backscattering and desorption are determined.
• Successive acceleration of positive and negative ions for space propulsion
  
  • Popelier Lara
  • Renaud Denis
  • Aanesland Ane
  , 2012.
• Design and Testing of a Surface Switch for the Dynamic Load Current Multiplier on the SPHINX Microsecond LTD Driver
  
  • Maysonnave Thomas
  • Bayol Frédéric
  • Demol Gauthier
  • d'Almeida Thierry
  • Morell Alain
  • Lassalle Francis
  • Grunenwald Julien
  • Chuvatin Alexandre S.
  • Pecastaing Laurent
  • de Ferron Antoine Silvestre
  , 2012. SPHINX is a microsecond linear transformer driver located at Atomic Energy Comission (CEA) Gramat (France), which can deliver a current pulse of 6 MA within 800 ns in a Z -pinch load. Using the concept of the dynamic load current multiplier (DLCM), which was proposed by Chuvatin, we expect to increase the load current above 6 MA, while decreasing its rise time to ~ 300 ns. The DLCM developed by the CEA Gramat and International Technologies for High Pulsed Power (ITHPP) is a compact system made up of concentric electrodes (autotransformer), a dynamic flux extruder (cylindrical wire array), a vacuum convolute (eight post-hole rods), and a closing switch (compact vacuum surface switch). The latter is a key component of the system, which is used to prevent the current from flowing into the load until the inductance builds up due to the implosion of the wire array. This paper presents the design and testing of the DLCM surface switch, resulting from both electrostatic simulations and experiments on the SPHINX generator. These studies, carried out either with or without load (open circuit), were valuable for a first experimental evaluation of the DLCM scheme in a microsecond regime and provided detailed information on the surface switch behavior.
• Evidence of different backstreaming populations in the quasi-perpendicular ion foreshock : 2D full particle simulation results
  
  • Savoini Philippe
  • Lembège Bertrand
  • Stienlet J.
  , 2012. Many space missions have already evidenced the existence of the foreshock region located upstream of the terrestrial bow shock and populated by energetic backstreaming particles (electrons and ions) issued from the shock. In order to analyse the foreshock region, a curved shock is simulated with the help of a 2-D full particle (PIC) code, where full curvature and time of flight effects are fully described by a self consistent approach. The analysis is restricted to the quasi-perpendicular angular range defined by 45° ≤ QBn ≤ 90°. Herein, we focus on the ion foreshock. In a good agreement with experimental data, present preliminary results evidence two distinct ion populations collimated along the interplanetary magnetic field (IMF): (i) the Field-Aligned Beam population (hereafter named "FAB'') and (ii) the gyro-phase bunch population (hereafter named "GPB'') which differ from each other by their gyrotropic or non-gyrotropic behavior, respectively. The analysis shows that no pitch angle scattering mechanism needs to be invoked to account for the generation of the "GPB''. Present results show that additional criteria are necessary namely: the interaction time Dint of backstreaming ions with the shock front and their downstream penetration depth. These criteria allow to evidence that the "FAB'' population correspond to particles which move back and forth between the upstream edge of the front and the overshoot, and are characterized by a quite large Dint (covering several local gyro-periods). In contrast, the "GPB'' ions have suffered a very short interaction time (i.e. less than one gyro-period) and escaped into the upstream region with a parallel velocity lightly higher than the "FAB'' population. "GPB'' particles seem to be produced by the electrostatic field built up at the shock front and are emitted in a burst-like mode rather than in continuous way.
• Finite-N Hamiltonian dynamics in long-range interacting systems
  
  • Ettoumi Wahb
  • Firpo Marie-Christine
  , 2012.
• Very Low 1/f Noise and Radiation-Hardened CMOS Preamplifier for High-Sensitivity Search Coil Magnetometers
  
  • Rhouni Amine
  • Sou Gérard
  • Leroy Paul
  • Coillot Christophe
  IEEE Sensors Journal, Institute of Electrical and Electronics Engineers, 2012, 13 (1), pp.159-166. A 4 nV/√(Hz) at 10 Hz preamplifier with a 12-mW power consumption in complimentary metal-oxide-semiconductor 0.35 μm technology has been developed to go one step further in the integration of the preamplifier of a search coil magnetometer. The present application-specific integrated circuit (ASIC) preamplifier, combined with a 10-cm length, 12-mm diameter, and 15 000 turns search coil sensor demonstrates a noise equivalent magnetic induction as low as 2 pT/√(Hz) at 10 Hz and 14 fT/√(Hz) at 4 kHz. The measured current noise is only 46 fA/√(Hz). AC magnetometers (from 100 mHz to a few kHz) based on search coil sensors are used for space plasma physics investigations because of their excellent robustness and very high sensitivity. The present ASIC preamplifier offers a way to considerably save weight, volume, and power. This paper will focus on the design of the ASIC, driven by the following criteria: low thermal and 1/f noise, radiation hardness for space purpose, and power consumption. (10.1109/JSEN.2012.2211347)
  DOI : 10.1109/JSEN.2012.2211347
• Capteurs et dispositifs électroniques des magnétomètres dédiés à l'étude des ondes dans les plasmas spatiaux.
  
  • Coillot Christophe
  , 2012. Capteurs et dispositifs électroniques des magnétomètres dédiés à l'étude des ondes dans les plasmas spatiaux.
• Transient fields produced by a cylindrical electron beam flowing through a plasma
  
  • Firpo Marie-Christine
  Laser and Particle Beams, Cambridge University Press (CUP), 2012, 30 (03), pp.497-507. The out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire, is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions. (10.1017/S0263034612000432)
  DOI : 10.1017/S0263034612000432
• Systematic propagation analysis of whistler-mode waves in the inner magnetosphere
  
  • Santolík O.
  • Gurnett D. A.
  • Pickett J. S.
  • Cornilleau-Wehrlin Nicole
  • Kolmasova Ivana
  • Macusova E.
  , 2012, 39, pp.1673. Acceleration and dynamics of energetic electrons in the outer Van Allen radiation belt can be influenced by cross-energy coupling among the particle populations in the radiation belts, ring current and plasmasphere. Waves of different frequencies have been shown to play a significant role in these interactions. We analyze more than 10 years of measurements of the four Cluster spacecraft to investigate propagation properties of whistler-mode waves in the crucial regions of the Earth's magnetosphere. We use this unprecedented database to determine the distribution of the wave energy density in the space of the wave vector directions, which is a crucial parameter for modeling of both the wave-particle interactions and wave propagation in the inner magnetosphere. We show implications for radiation belt studies and upcoming inner magnetosphere spacecraft missions, and we also show similarities of the observed whistler-mode waves with results from the magnetosphere of Saturn collected by the Cassini mission.
• Signature of the coronal hole near the north crest equatorial anomaly over Egypt during the strong geomagnetic storm 5 April 2010
  
  • Shimeis Amira
  • Fathy Ibrahim
  • Amory-Mazaudier Christine
  • Fleury Rolland
  • Mahrous Ayman Mohamed
  • Yumoto Kiyohumi
  • Groves K.
  Journal of Geophysical Research, American Geophysical Union, 2012, 117 (A7), pp.1-8. In this paper we study the ionospheric-magnetic disturbance during a strong magnetic storm on 5 April 2010 associated to a coronal hole. The Earth was under the influence of a high speed solar wind stream during four days, and IMF was southward during a very long period. The variation of the disturbed magnetic observations and GPS-TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS-TEC and magnetic disturbances due to the coronal hole effect. We use multi-instruments as SCINDA-GPS station at Helwan, Egypt (29.86 N, 31.32 E) and ASW-MAGDAS station at Aswan, Egypt (23.59 N, 32.51 E) in the equatorial region. At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storm, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti-Sq circulation on magnetic data during four consecutive days associated to the high speed solar wind streams. (10.1029/2012JA017753)
  DOI : 10.1029/2012JA017753
• Surface mechanisms investigation for negative ion production
  
  • Béchu Stéphane
  • Soum-Glaude A.
  • Bès A.
  • Svarnas P.
  • Bacal M.
  • Lacoste A.
  , 2012, pp.P 2.1.1.
• Streamers and discharges at liquid and solid interfaces
  
  • Rousseau Antoine
  , 2012. http://escampig2012.ist.utl.pt
• Spectroscopic and shadowgraphic investigation of nanosecond underwater discharge
  
  • Marinov Ilya
  • Starikovskaia Svetlana
  • Rousseau Antoine
  , 2012.
• Probing adsorption and reactivity of nitrogen atoms on silica surface under plasma exposure
  
  • Marinov Daniil
  • Guaitella Olivier
  • Corbella C.
  • Arcos T. de Los
  • von Keudell A.
  • Rousseau Antoine
  , 2012.
• Optical-Feedback Cavity-Enhanced Absorption spectroscopy detects ppt traces of Formaldehyde for the validation of air plasma treatment system
  
  • Fasci Eugenio
  • Guaitella Olivier
  • Gorrotxategi Carbajo P.
  • Ventrillard I.
  • Carras M.
  • Maisons G.
  • Romanini D.
  • Rousseau Antoine
  , 2012.
• Consequences of slightly different ground configurations on the propagation of ionisation waves inside capillary tubes
  
  • Guaitella Olivier
  • Rousseau Antoine
  , 2012.
• Experimental study of fast gas heating in a capillary nanosecond discharge
  
  • Klochko A.V.
  • Lemainque J.
  • Starikovskaia Svetlana
  , 2012.
• Surface vibrational relaxation of N<SUB>2</SUB> studied by infrared titration with time resolved Quantum Cascade Laser diagnostics
  
  • Marinov Daniil
  • Lopatik D.
  • Hübner M.
  • Ionikh Y.
  • Roepcke J.
  • Rousseau Antoine
  , 2012.