Publications

2012

Ozone production in O2 plasma at low pressure: surface or gas phase mechanism?
- Marinov Daniil
- Guerra V.
- Guaitella Olivier
- Rousseau Antoine
, 2012.
Molecules formation at surfaces
- Guaitella Olivier
, 2012. http://escampig2012.ist.utl.pt
Electric field evolution in surface nanosecond discharge
- Stepanyan S.A.
- Kosarev I.N.
- Starikovskaia Svetlana
, 2012.
Evolution of electron temperature and negative ion density through a magnetic barrier
- Bredin Jérôme
- Popelier Lara
- Godyak Valery
- Chabert Pascal
- Aanesland Ane
, 2012.
Space charge neutralisation of continuous dual ion beams
- Aanesland Ane
- Popelier Lara
- Oudini N.
- Chabert Pascal
, 2012.
One-dimensional Particle-In-Cell simulations of the sheath dynamic in ion-ion plasmas
- Oudini N.
- Meige A.
- Aanesland Ane
- Raimbault Jean-Luc
- Chabert Pascal
- Garrigues Laurent
- Hagelaar G J M
, 2012.
Gas temperature and electron density measurements in Ar and Ar-Cl2 ICP discharges
- Booth Jean-Paul
- Sirse Nishant
- Délivré Quentin
- Chabert Pascal
, 2012.
Spectroscopic and shadowgraphic investigation of nanosecond underwater discharge
- Marinov Ilya
- Starikovskaia Svetlana
- Rousseau Antoine
, 2012.
Streamers and discharges at liquid and solid interfaces
- Rousseau Antoine
, 2012. http://escampig2012.ist.utl.pt
Application of VisRad modeling to design of hohlraum experiments on Zebra with enhanced current
- Shlyaptseva V. V.
- Kantsyrev Viktor L.
- Esaulov A. A.
- Safronova Alla S.
- Chuvatin Alexandre S.
- Rudakov Leonid I.
- Macfarlane J. J.
- Golovkin I. E.
, 2012, pp.2P87. VisRad (Prism Computational Sciences), a 3-D view factor code, is used to simulate the multi-dimensional radiation environment within a compact hohlraum. A new hohlraum design proposed in B. Jones, et al. [PRL, v.104, 125001, (2010)] incorporates multiple compact (mm-scale) planar wire array (PWA) x-ray sources that surround a target in the center of the hohlraum cavity, allowing a reduction of hohlraum surface area and potentially providing a hotter x-ray environment. The first experiments with this prototype of hohlraum with two magnetically-decoupled PWA sources were performed on the 1.7 MA Zebra at the University of Nevada, Reno without significant loss of radiation yields and power due to implementation of a new Load Current Multiplier (LCM). VisRad simulations have predicted a center hohlraum radiation temperature >; 30eV, showing good correlation to experimental EUV data (hν >; 17 eV). Special emphasis is made on Trad and uniformity at the test target surface. Also discussed is the scaling of the new hohlraum multisource configurations using VisRad for higher current, 20 MA-scale generators.
DISTRIBUTION OF SURFACE ELECTRIC CHARGE IN A SURFACE DBD
- Dong Binjie
- Guaitella Olivier
- Rousseau Antoine
, 2012.
Laser photo-detachment measurements in the ECR driven H-negative ion source PROMETHEUS I
- Aleiferis S.
- Svarnas P.
- Béchu Stéphane
- Bacal M.
- Lacoste A.
, 2012, pp.3P-50. Large interest is presently devoted to the development of high-power negative ion sources applicable to the International Thermonuclear Experimental Reactor (ITER) project. Hydrogen negative ions H- are efficiently used to generate neutral beams for heating magnetically confined fusion plasmas [1]. Despite the large scale of ITER project, dedicated bench-scale experiments try to optimize the different sources acting on the elementary processes at the basis of the production of negative ions [2]. Understanding the negative ion formation mechanisms requires diagnostic techniques which can determine the absolute density of the hydrogen negative ions in the bulk plasma of these sources [3]. Photo-detachment is possibly the most convenient method towards this direction [3,4]. In the frame of the above concept and as continuity of our recent research (e.g. [5,6]), a new H- negative ion source named PROMETHEUS I has been installed in the High Voltage Laboratory of the University of Patras. The source is based on a cubic [(240 mm)3] stainless steel high vacuum chamber (base pressure 1.5x10-6 Torr). Instead of traditional filaments, the power is delivered by five elementary plasma sources sustained at electron cyclotron resonance (ECR) [7], due to a combination of microwaves (2.45 GHz) and static magnetic fields (875 G). Furthermore, rather than conventional magnetrons, the microwaves are produced by PC-controlled solid state components. In this work, this new source is probed by means of single beam laser photo-detachment technique. The plasma is locally disturbed by photons of 1.2 eV energy and the electrons photo-detached from the H- ions are collected by a thin cylindrical electrostatic probe. The H- density is eventually calculated for various working pressures (up to 10 mTorr) and microwave powers (up to 1 kW), providing an efficient operational window of the source. The full process, including the calibration method in order to achieve full conversion of H- ions into photo-electrons along the laser beam path, is as well considered herein. (10.1109/PLASMA.2012.6383834)
DOI : 10.1109/PLASMA.2012.6383834
Ion-ion plasma in propulsion and processing applications
- Oudini N.
- Meige A.
- Chabert Pascal
- Aanesland Ane
, 2012.
Gas temperature measurement in Ar and Ar-Cl2 based ICP discharge: Comparison between experiments and simulations
- Sirse Nishant
- Délivré Quentin
- Booth Jean-Paul
- Chabert Pascal
, 2012.
Study of a prototype of a new compact hohlraum configuration at the 1.7 MA UNR zebra generator
- Kantsyrev Viktor L.
- Safronova V. V.
- Esaulov A. A.
- Shrestha Ishor
- Osborne Glenn C.
- Shlyaptseva V. V.
- Weller Michael E.
- Zunino H. A.
- Chuvatin Alexandre S.
- Rudakov Leonid I.
- Velikovich A. L.
- Jones B.
- Vesey R. A.
, 2012, pp.2C1. A new hohlraum configuration for radiation physics/ICF was proposed [B. Jones et al., PRL 104, 125001 (2010)]. Multiple compact (mm-scale) planar wire array (PWA) sources that surround a central hohlraum allow reduced hohlraum surface area and potentially provide a hotter x-ray environment than in a double-ended scheme with cylindrical arrays. The current multiplication technique became possible because of high impedance of Zebra and increase of the current up to 1.7 MA. We have demonstrated previously that the PWA plasma at stagnation dissipates the magnetic energy greater than ΔL*I2/ 2, operating mainly as a resistor R(t) [V. Kantsyrev et al., Dense Z-pinch 2011 CP]. This allowed us to redistribute the generator current between two magnetically decoupled PWA without significant loss of radiation yields. With half the current flowing through each PWA, the kinetic energy Ek coupled to it, which scales as I2, will be 1/4 of the energy coupled to a single PWA carrying the same total current and experiencing the same change of inductance ΔL at implosion. The total Ek delivered to two PWAs at stagnation would thereby be 1/2 of Ek delivered to a single PWA. In experiment, the current was split between two decoupled sources (0.75 MA to each), and the total yield EΣ was at least 85 % compared to total yield ET from single PWA at 1.6 MA. Then, new hohlraum configuration with two decoupled PWAs was tested. The VisRad code (Prism Comp. Sci.) predicted hohlraum radiation temperature >30 eV which correlates with strong hohlraum output radiation (hυ > 17 eV). Scaling using VisRad on different hohlraum multisource configurations for higher current 20 MA scale generators is discussed. The experimental comparison of planar foil liners (another promising x-ray radiator) with PWAs is also presented. (10.1109/PLASMA.2012.6383534)
DOI : 10.1109/PLASMA.2012.6383534
Triggering and Guiding of High-Voltage Tesla Coil Discharges by Femtosecond Laser-Induced Plasma Filaments in Air
- Brelet Yohann
- Houard Aurélien
- Arantchouk Léonid
- Prade Bernard S.
- Carbonnel Jérôme
- André Y-B.
- Mysyrowicz André
, 2012. oral presentation
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 (P1.069). ocs.ciemat.es/epsicpp2012pap/pdf/P1.069.pdf
Deconvolution of collective scattering signal measured on Hall thruster plasma
- Cavalier J.
- Lemoine N.
- Tsikata Sedina
- Honoré Cyrille
- Grésillon D.
- Bonhomme Gildas
, 2012 (P1.008).
Spatio-temporal fluctuation spectra in the Hall thruster plasma : electron density and the induced electron transport
- Honoré Cyrille
- Grésillon D.
- Cabriel C.
- Tsikata Sedina
- Héron A.
- Lemoine N.
- Cavalier J.
, 2012 (P5.142).
Investigation of Voltage Waveform Tailoring Effect in CapacitivelyCoupled H2 Discharge: Fluid Simulations and Experimental Validation
- Novikova T.
- Johnson E.V.
- Mao M.
- Bulkin P.
- Booth Jean-Paul
- Cabarrocas P. Roca I
, 2012.
Numerical simulations of a new-type axial vircator with a reflector for enhanced efficiency
- Champeaux Stéphanie
- Gouard Philippe
- Cousin Richard
- Larour Jean
, 2012, pp.41. Oral presentation. A new type of axial vircator with reflector is numerically simulated with a PIC code for the first time. The power conversion efficiency of classical vircator is shown to be enhanced from 1% to 4.8%. Optimization of both reflector position and radius is expected to increase performances. http://www.ece.unm.edu/summa/notes/AMEREM-EUROEM/EUROEM2012-final-10July2012NPA -SUMMA.pdf
Induction magnetometer using a low noise ASIC from sensor to ADC: design, performances and limitation
- Rhouni Amine
- Coillot Christophe
- Sou Gérard
- Leroy Paul
, 2012.
A nighttime temperature maximum in the thermosphere above Saint Santin in winter
- Oliver W. L.
- Martinis C. R.
- Hickey D.A.
- Wright A.D.
- Amory-Mazaudier Christine
Journal of Geophysical Research, American Geophysical Union, 2012, 117, pp.1-10. The Saint Santin (45 N) incoherent scatter radar data base shows a local enhancement in nighttime ion temperature that occurs in winter only. Its amplitude can exceed 100 K and averages 40 K on the basis of a conservative computation. The enhancement peaks near 4 LT and has a duration of about 4 hours. We discuss two possible explanations for this feature: (1) it is caused by the convergence of global winds at the global pressure minimum, under which Saint Santin rotates at winter solstice, and (2) it is an extension or propagation of the well-known low-latitude midnight temperature maximum to midlatitudes, perhaps to that pressure minimum. (10.1029/2012JA017855)
DOI : 10.1029/2012JA017855
Plasma-assisted combustion and combustion kinetics. Review of experimental and theoretical works
- Starikovskaia Svetlana
, 2012.
Coupling the solar surface and the corona: Coronal rotation, Alfvén wave-driven polar plumes
- Pinto Rui F
- Grappin Roland
- Velli Marco
- Verdini Andrea
, 2013, 1539, pp.58-61. The dynamical response of the solar corona to surface and sub-surface perturbations depends on the chromospheric stratification, and specifically on how efficiently these layers reflect or transmit incoming Alfvén waves. While it would be desirable to include the chromospheric layers in the numerical simulations used to study such phenomena, that is most often not feasible. We defined and tested a simple approximation allowing the study of coronal phenomena while taking into account a parametrised chromospheric reflectivity. We addressed the problems of the transmission of the surface rotation to the corona and that of the generation of polar plumes by Alfvén waves [1, 2]. We found that a high (yet partial) effective chromospheric reflectivity is required to properly describe the angular momentum balance in the corona and the way the surface differential rotation is transmitted upwards. Alfvén wave-driven polar plumes maintain their properties for a wide range of values for the reflectivity, but they become bursty (and eventually disrupt) when the limit of total reflection is attained. (10.1063/1.4810989)
DOI : 10.1063/1.4810989

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