Publications

2011

• Fast gas heating in nitrogenoxygen discharge plasma: II. Energy exchange in the afterglow of a volume nanosecond discharge at moderate pressures
  
  • Mintoussov E I
  • Pendleton S J
  • Gerbault F
  • Popov N A
  • Starikovskaia S M
  Journal of Physics D: Applied Physics, IOP Publishing, 2011, 5 (28), pp.285202-564. gas heating in nitrogen-oxygen discharge plasma. II. Energy exchange in the afterglow of a volume nanosecond discharge at moderate pressures. Abstract. The process of fast gas heating in air in the near afterglow of a pulsed nanosecond spatially uniform discharge has been investigated experimentally and numerically at moderate (3−9 mbar) pressures and high (200−400 Td) reduced electric fields. The temporal behavior of discharge current, deposited energy, electric field and temperature were measured. The role of processes with participation of excited and charged species was analyzed. It was shown that under the considered conditions the main energy release takes place in reactions of nitrogen and oxygen dissociation by electron impact and quenching of electronically excited nitrogen molecules, such as N 2 (A 3 Σ + u, B 3 Π g, C 3 Π u, a ' 1 Σ − u) by oxygen and quenching of excited O(1 D) atoms by N 2. It was shown that about 24% of the discharge energy goes to fast gas heating during first tens of microseconds after the discharge. (10.1088/0022-3727/44/28/285202)
  DOI : 10.1088/0022-3727/44/28/285202
• Maximum entropy production principle
  
  • Berionni Vincent
  • Gürcan Özgür D.
  , 2011.
• Entropy production and H-theorems for turbulence
  
  • Gürcan Özgür D.
  , 2011.
• Electron scale physics in collisionless space plasma: Recent Cluster observations and theoretical modeling
  
  • Goldstein M. L.
  • Huang S. Y.
  • Sahraoui Fouad
  • Belmont Gérard
  , 2011.
• Renormalization of the transport due to toroidal ITG turbulence
  
  • Gürcan Özgür D.
  , 2011.
• Fluctuation-induced electron mobility in the observed turbulent E-field of the Hall effect thruster
  
  • Grésillon D.
  • Honoré Cyrille
  • Tsikata Sedina
  , 2011 (P2.018).
• Impact of collisionality on characteristics of micro-turbulence on Tore Supra
  
  • Vermare Laure
  • Hennequin Pascale
  • Gürcan Özgür D.
  • Honoré Cyrille
  • Bourdelle C.
  • Clairet F.
  • Garbet X.
  • Giacalone J-C.
  • Sabot R.
  • Sarazin Y.
  • Goërler T.
  • Jenko F.
  , 2011 (O4.126). (oral)
• Anisotropy and pulse shaping of radiation emitted from multi-planar wire arrays
  
  • Kantsyrev Viktor L.
  • Esaulov A. A.
  • Safronova Alla S.
  • Rudakov Leonid I.
  • Chuvatin Alexandre S.
  • Velikovich A. L.
  • Williamson Kenneth M.
  • Osborne Glenn C.
  • Shrestha Ishor
  • Weller Michael E.
  • Shlyaptseva V. V.
  • Stafford A.
  , 2011, pp.1. Summary form only given. Compact double and triple planar wire arrays (DPWA and TPWA) demonstrated the largest resistive energy and power gain, and the highest current scaling among all tested loads at the UNR Zebra generator. Knowledge of the spatial distribution of x-ray radiation from the plasma source is crucial for ICF and radiation physics applications of PWAs [B. Jones et al., PRL, v. 104, 125001 (2010)]. New experiments indicated anisotropic emission from PWAs. Experiments were performed on the UNR Zebra generator with a peak current increased from 0.9 up to 1.7 MA by application of a new load current multiplier (LCM) developed and tested in collaboration with Ecole Polytechnique, France, and Sandia National Laboratories. For SPWAs, the total yield registered orthogonally to the array plane (E&#8869;) was higher than measured along the plane (E&#8741;) and anisotropy ratio was (E&#8869;/E&#8741; <; 1.7). For DPWAs and TPWAs, the same ratio was a little less, <;1.25 for DPWAs and up to 1.35 for TPWAs. This can be explained by intense absorption of x-ray radiation in the direction of cold trailing mass plasma collected during implosion along the array plane (for SPWAs) and in a direction perpendicular to the array planes (for DPWAs or TPWAs). Another observation that supports the opacity effects for SPWAs was that the time interval between the current start and the moment when the sub-keV radiation pulse began was found to be greater for registration along the array plane compared to collecting perpendicular to the plane (t&#8741; >; t&#8869;). The &#916;tSPWA was from 3 to 10 ns. However, it was opposite for DPWA (t&#8869; >; t&#8741; and &#916;tDPWA was up to 8 ns). New results were obtained on x-ray pulse shaping from PWAs. Experiments with DPWA with straight and skewed wires and TPWA have shown a different set- of pulse shapes (pre-pulses and pulse steps on front of sub-keV burst). The results were in qualitative agreement with predictions made using Wire Ablation Dynamic Model. Future directions of research are discussed. (10.1109/PLASMA.2011.5992969)
  DOI : 10.1109/PLASMA.2011.5992969
• Solar wind turbulence: analysis at different scales, Waves and Instabilities in Space Plasmas
  
  • Rezeau Laurence
  • Sahraoui Fouad
  • Panis Jean-François
  • Belmont Gérard
  , 2011. Magnetic turbulence in the solar wind has been studied since the beginning of space exploration by several spacecraft such as Voyager, Helios, Ulysses, Wind and Stereo. More recently, a real breakthrough has been made in understanding this turbulence thanks to the multi-point Cluster measurements. Using appropriate multi-spacecraft techniques, such as the so-called k-filtering technique, it has been possible to compute 3D wave-number spectra of the turbulence both at MHD scales (L>>&#61554;i, &#61554;i being the ion Larmor radius) and at sub-proton scales (L<&#61554;i) [Narita PRL, 2010; Sahraoui et al., PRL 2010]. Moreover, thanks to the use of high time resolution of the Cluster magnetic field data (up to 100Hz in the spacecraft reference frame), it has been possible for the first time to probe the electron scales where a new kinetic cascade and dissipation has been revealed [Sahraoui et al., PRL 2009, Alexandrova PRL., 2009]. Besides these analyses of power spectra (i.e. the 2nd order moment of the PDFs) other analyses involving the phase can be performed. This is mandatory to understand the role of non-linear effects in the different domains and to investigate the possibility of an energy cascade through different scales (ion and electron scales). Two different methods are applied to diagnose the degree of phase coherence - which is related to the degree of nonlinearities - of the turbulent signals (using single spacecraft data). One is a direct statistical analysis of the phase gradients; the other is the comparison with a surrogate signals through computation of structure functions. These methods will be presented with application to simulations and real data in the solar wind.
• In situ observations of magnetic reconnection in near-Earth space
  
  • Retinò Alessandro
  • Vaivads A.
  • Sahraoui Fouad
  • Nakamura R.
  • Fujimoto M.
  • Sundkvist D.
  • Mozer F. S.
  , 2011.
• Cascade and dissipation of solar wind turbulence from MHD to electron scales: Recent Cluster observations and theoretical modeling
  
  • Sahraoui Fouad
  • Belmont Gérard
  • Goldstein M. L.
  • Huang S. Y.
  • Kiyani K. H.
  • Retinò Alessandro
  , 2011.
• Advanced load current multiplier on Zebra generator
  
  • Chuvatin Alexandre S.
  • Kantsyrev Viktor L.
  • Astanovitsky A. L.
  • Presura Radu
  • Safronova Alla S.
  • Le Galloudec B.
  • Nalajala Vidya
  • Williamson Kenneth M.
  • Shrestha Ishor
  • Osborne Glenn C.
  • Weller Michael E.
  • Shlyaptseva V. V.
  • Rudakov Leonid I.
  • Cuneo Michael E.
  , 2011, pp.975-982. An improved load current multiplier (LCM) was designed and tested on a high-voltage 100 ns, 0.8-1 MA generator Zebra. The new design allowed to achieve up to ~1.7 MA in plasma loads and up to 1.9 MA in static loads [1]. The previous LCM version provided 1.4 and 1.6 MA accordingly [2]. The load current increase results in the increase of X-ray yield and power from plasma radiation source loads [3]. The advanced LCM represents an integral part of Zebra, inside the generator vacuum section. The new low-inductance design of LCM-to-load connection ensured shielding of the multiplier convolute from load events. Experiments with plasma loads were thus possible without after-shot dismounting of LCM for load installation and diagnostics arrangement. Validation of LCM's on a high-voltage nanosecond generator suggests that the concept could be applicable to existing and future multi-MA fast pulse-power drivers. Anticipating these applications, we present first estimates supporting scaling-up of the LCM technique to multi-terawatt facilities. (10.1109/PPC.2011.6191628)
  DOI : 10.1109/PPC.2011.6191628
• Extraction and acceleration of ions from an ion-ion plasma - application to space propulsion
  
  • Popelier Lara
  • Aanesland Ane
  • Mazouffre S.
  • Chabert Pascal
  , 2011, pp.708-711. Recent progress in the ion acceleration from the PEGASES thruster ion-ion region is presented here. Preliminary to positive and negative ions acceleration from an ion-ion plasma, the acceleration scheme is investigated in an Argon plasma. With time-averaged Langmuir probe and RFEA. (10.1109/RAST.2011.5966933)
  DOI : 10.1109/RAST.2011.5966933
• In situ observations of magnetic reconnection in near-Earth space
  
  • Retinò Alessandro
  • Sahraoui Fouad
  • Vaivads A.
  • Sundkvist D.
  • Mozer F. S.
  • Nakamura R.
  • Zieger B.
  • Fujimoto M.
  • Tanaka K.
  , 2011.
• Producing keV Plasmas on Zebra at UNR: achievements, challenges and applications
  
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Esaulov A. A.
  • Shrestha Ishor
  • Shlyaptseva V. V.
  • Weller Michael E.
  • Ouart N. D.
  • Osborne Glenn C.
  • Williamson Kenneth M.
  • Keim S. F.
  • Velikovich A. L.
  • Giuliani J. L.
  • Chuvatin Alexandre S.
  , 2011.
• Developments of capillary discharge for laser plasma accelerators
  
  • Arantchouk Léonid
  • Corde S.
  • Thaury C.
  • Ta Phuoc K.
  • Lambert G.
  • Rechatin C.
  • Faure J.
  • Lundh O.
  • Benveniste E.
  • Ben-Ismail A.
  • Larour Jean
  • Marciniak A.
  • Stordeur A.
  • Prithviraj B.
  • Specka A.
  • Malka V.
  , 2011. présentation orale
• k spectra in Tore Supra : experiments, theory and modelling
  
  • Hennequin Pascale
  , 2011.
• VOLTAGE WAVEFORM TAILORING: A PROMISING NEW METHOD FOR SILICON DEPOSITION
  
  • Delattre Pierre-Alexandre
  • Pouliquen S.
  • Johnson E.V.
  • Sirse Nishant
  • Booth Jean-Paul
  , 2011.
• Anisotropy of Radiation Emitted from Multi-Planar Wire Arrays and their new applications for radiation physics and ICF
  
  • Kantsyrev Viktor L.
  • Chuvatin Alexandre S.
  • Esaulov A. A.
  • Safronova Alla S.
  • Rudakov Leonid I.
  • Velikovich A. L.
  • Shrestha I. K.
  • Osborne Glenn C.
  • Williamson Kenneth M.
  • Weller Michael E.
  • Shlyaptseva V. V.
  • Astanovitsky A.
  • Nalajala Vidya
  • Dmitriev O.
  • Ouart N .D.
  • Stafford A.
  • Keim S.
  , 2011.
• Overview of moons ionized environments (Europa, Ganymede, Callisto),
  
  • Fontaine Dominique
  , 2011.
• MESURE DE TEMPERATURE DU GAZ DANS UN RÉACTEUR DE GRAVURE DOUBLE FRÉQUENCES CAPACITIF
  
  • Booth Jean-Paul
  • Bjelogrlic Wladimir
  • Bredin Jérôme
  , 2011.
• Physique des réacteurs plasmas radiofréquence
  
  • Chabert Pascal
  , 2011.
• Stochastic treatment of finite-N fluctuations in the approach towards equilibrium for mean field models
  
  • Ettoumi Wahb
  • Firpo Marie-Christine
  , 2011.
• Interplay of Magnetic Shear and Resonances in Magnetic Fusion Devices
  
  • Firpo Marie-Christine
  • Constantinescu D.
  , 2011. The dual impact of low magnetic shear is shown in a unified way with extension to non-axisymmetric states. Away from resonances, it induces a drastic enhancement of magnetic confinement that favors robust internal transport barriers (ITBs) and turbulence reduction. When low-shear occurs for values of the winding of the magnetic field lines close to low-order rationals, the amplitude thresholds of the resonant modes that break internal transport barriers by allowing a radial stochastic transport of the magnetic field lines may be quite low. This analysis puts a constraint on the tolerable mode amplitudes compatible with ITBs and is shown to be consistent with diverse experimental and numerical signatures of their collapses.
• Shadowgraphic and spectroscopic diagnostics of the nanosecond underwater discharges
  
  • Marinov Ilya
  • Guaitella Olivier
  • Rousseau Antoine
  • Starikovskaia Svetlana
  , 2011.