Publications

2016

• Cone angle control of the interaction of magnetic clouds with the Earth's bow shock
  
  • Turc Lucile
  • Escoubet C. Philippe
  • Fontaine Dominique
  • Kilpua E. K. J.
  • Enestam S.
  Geophysical Research Letters, American Geophysical Union, 2016, 43, pp.4781-4789. Not Available (10.1002/2016GL068818)
  DOI : 10.1002/2016GL068818
• Distinct responses of the low-latitude ionosphere to CME and HSSWS: The role of the IMF B^z oscillation frequency
  
  • Rodríguez-Zuluaga J.
  • Radicella S. M.
  • Nava B.
  • Amory-Mazaudier Christine
  • Mora-Páez H.
  • Alazo-Cuartas K.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2016. In this work an attempt to identify the role of the interplanetary magnetic field (IMF) in the response of the ionosphere to different solar phenomena is presented. For this purpose, the day-today variability of the equatorial ionospheric anomaly (EIA) and the main ionospheric disturbances are analyzed during one coronal mass ejection (CME) and two high-speed solar wind streams (HSSWSs). The EIA parameters considered are the zonal electric field and both the strength and position of its northern crest. The disturbances being the prompt penetration of magnetospheric electric field (PPMEF) and disturbance dynamo electric field (DDEF) are studied using the magnetic response of their equivalent current systems. In accordance, ground-based Global Navigation Satellite Systems receivers and magnetometers at geomagnetic low latitudes in the American sector are used. During both phenomena, patterns of PPMEF related to fluctuations of the IMF are observed. Diurnal and semidiurnal magnetic oscillations are found to be likely related to DDEF. Comparisons among the EIA parameters and the DDEF magnetic response exhibit poor relation during the CME in contrast to good relation during the HSSWSs. It is concluded that the response of the low-latitude ionosphere to solar phenomena is largely determined through the oscillation frequency of the IMF B z by affecting the generation of the PPMEF and DDEF differently. This is seen as an effect of how the energy from the solar wind is transferred into the magnetosphere-ionosphere system. (10.1002/2016JA022539)
  DOI : 10.1002/2016JA022539
• Etude in-situ de la magnétopause Terrestre, de Cluster à MMS
  
  • Rezeau Laurence
  • Manuzzo Roberto
  • Belmont Gérard
  • Califano F.
  , 2016.
• Impact of the Eulerian chaos of magnetic field lines in magnetic reconnection
  
  • Firpo Marie-Christine
  • Ettoumi Wahb
  • Lifschitz A. F.
  • Retinò Alessandro
  • Farengo R F
  • Ferrari H E
  • García-Martínez P L
  Physics of Plasmas, American Institute of Physics, 2016, 23 (12). Stochasticity is an ingredient that may allow the breaking of the frozen-in law in the reconnec-tion process. It will first be argued that non-ideal effects may be considered as an implicit way to introduce stochasticity. Yet there also exists an explicit stochasticity that does not require the invocation of non-ideal effects. This comes from the spatial (or Eulerian) chaos of magnetic field lines that can show up only in a truly three-dimensional description of magnetic reconnection since two-dimensional models impose the integrability of the magnetic field lines. Some implications of this magnetic braiding, such as the increased particle finite-time Lyapunov exponents and increased acceleration of charged particles, are discussed in the frame of tokamak sawteeth that form a laboratory prototype of spontaneous magnetic reconnection. A justification for an increased reconnection rate with chaotic vs integrable magnetic field lines is proposed. Moreover, in 3D, the Eulerian chaos of magnetic field lines may coexist with the Eulerian chaos of velocity field lines, that is more commonly named turbulence. (10.1063/1.4972544)
  DOI : 10.1063/1.4972544
• Double and Single Planar Wire Arrays on University-Scale Low-Impedance LTD Generator
  
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Weller Michael E.
  • Shlyaptseva V. V.
  • Shrestha I. K.
  • Lorance M. Y.
  • Schmidt-Petersen M. T.
  • Stafford A.
  • Cooper M. C.
  • Steiner A. M.
  • Yager-Elorriaga D. A.
  • Patel S. G.
  • Jordan N. M.
  • Gilgenbach R. M.
  • Chuvatin Alexandre S.
  IEEE Transactions on Plasma Science, Institute of Electrical and Electronics Engineers, 2016, 44 (4), pp.432-440. Planar wire array (PWA) experiments were performed on Michigan Accelerator for Inductive Z-pinch Experiments, the University of Michigan's low-impedance linear transformer driver (LTD)-driven generator (0.1 Ω, 0.5-1 MA, and 100-200 ns), for the first time. It was demonstrated that Al wire arrays [both double PWA (DPWA) and single PWA (SPWA)] can be successfully imploded at LTD generator even at the relatively low current of 0.3-0.5 MA. In particular, implosion characteristics and radiative properties of PWAs of different load configurations [for DPWA from Al and stainless steel wires with different wire diameters, interwire gaps, and interplanar gaps (IPGs) and for Al SPWA of different array widths and number of wires] were studied. The major difference from the DPWA experiments on high-impedance Zebra accelerator was in the current rise time that was influenced by the load inductance and was increased up to about 150 ns during the first campaign (and was even longer in the second campaign). The implosion dynamics of DPWAs strongly depends on the critical load parameter, the aspect ratio (the ratio of the array width to IPG) as for Al DPWAs on high-impedance Zebra, but some differences were observed, for low-aspect ratio loads in particular. Analysis of X-ray images and spectroscopy indicates that K-shell Al plasmas from Al PWAs reached the electron temperatures up to more than 450 eV and densities up to 2 x 10²⁰ cm⁻³. Despite the low mass of the loads, opacity effects were observed in the most prominent K-shell Al lines almost in every shot. (10.1109/TPS.2016.2538291)
  DOI : 10.1109/TPS.2016.2538291
• Larger sized planar wire arrays of complex configuration on 1.51.8 MA Z-pinch generator
  
  • Safronova Alla S.
  • Kantsyrev Viktor L.
  • Weller Michael E.
  • Shlyaptseva V. V.
  • Shrestha I. K.
  • Stafford A.
  • Schmidt-Petersen M. T.
  • Lorance M. Y.
  • Schultz K. A.
  • Chuvatin Alexandre S.
  Physics of Plasmas, American Institute of Physics, 2016, 23, pp.101210. Two new approaches of (i) simultaneous study of implosion and radiative characteristics of different materials in wire array Z-pinch plasmas in one shot and (ii) investigation of larger sized wire arrays (to enhance energy coupling to plasmas and provide better diagnostic access) were developed in experiments with 1.51.8 MA Zebra with a Load Current Multiplier. In particular, the larger sized multi-plane Planar Wire Arrays with two outer planes placed at 9 and 15 mm from each other and then as far as at 19 mm (compared with 6 mm studied before at standard 1 MA current) and with a modified central plane with 8 to 12 empty slots were investigated. Though K-shell Al and L-shell Ni, Cu plasmas have similar electron temperatures and densities, the ablation dynamics and radiation of Al and Ni, Cu planes are somewhat different, which was investigated in detail using the full set of diagnostics and modeling. Advantages of using such wire arrays at higher currents to study plasma flow and radiation from different materials and jets are highlighted. (10.1063/1.4965239)
  DOI : 10.1063/1.4965239