Publications

2011

• INCLINE - Inductively coupled plasma for CMOS-compatible etching of III-V integrated laser sources
  
  • Bouchoule S.
  • Gatilova L.
  • Patriarche G.
  • Guilet S.
  • Le Gratiet L.
  • Vallier L.
  • Chabert Pascal
  • Booth Jean-Paul
  • Chanson R.
  • Rhallabi A.
  • Cardinaud C.
  • Rojo-Romeo P.
  • Leclercq J.-L.
  • Letartre X.
  , 2011.
• Cluster Observations of Magnetopause Reconnection at Sub-Proton Scales
  
  • Retinò Alessandro
  • Vaivads A.
  • Sahraoui Fouad
  • Le Contel Olivier
  • Zieger B.
  • Nakamura R.
  • Mozer F. S.
  , 2011.
• Edge Temperature Gradient as Intrinsic Rotation Drive in Alcator C-Mod Tokamak Plasmas
  
  • Rice J.E.
  • Hughes J.W.
  • Diamond P.H.
  • Kosuga Y.
  • Podpaly Y.A.
  • Reinke M.L.
  • Greenwald M.J.
  • Gürcan Özgür D.
  • Hahm T.S.
  • Hubbard A.E.
  • Marmar E.S.
  • Mcdevitt C.J.
  • Whyte D.G.
  Physical Review Letters, American Physical Society, 2011, 106, pp.215001. Intrinsic rotation has been observed in I-mode plasmas from the C-Mod tokamak, and is found to be similar to that in H mode, both in its edge origin and in the scaling with global pressure. Since both plasmas have similar edge ∇T, but completely different edge ∇n, it may be concluded that the drive of the intrinsic rotation is the edge ∇T rather than ∇P. Evidence suggests that the connection between gradients and rotation is the residual stress, and a scaling for the rotation from conversion of free energy to macroscopic flow is calculated. (10.1103/PhysRevLett.106.215001)
  DOI : 10.1103/PhysRevLett.106.215001
• Reactivity and adsorption of N atoms on catalytic surfaces
  
  • Marinov Daniil
  • Guaitella Olivier
  • Rousseau Antoine
  , 2011.
• Reactivity of atoms adsorbed on catalytic surfaces under plasma exposure
  
  • Marinov Daniil
  • Guaitella Olivier
  • Rousseau Antoine
  , 2011.
• Global distribution of electrostatic electron cyclotron harmonic waves observed on THEMIS
  
  • Ni B.
  • Thorne R. M.
  • Liang Jun
  • Angelopoulos V.
  • Cully C. M.
  • Li W.
  • Zhang Xiaojia
  • Hartinger Michael
  • Le Contel Olivier
  • Roux A.
  Geophysical Research Letters, American Geophysical Union, 2011, 38, pp.17105. A global, statistical analysis of electrostatic electron cyclotron harmonic (ECH) waves is performed using THEMIS wave data. Our results confirm the high occurrence of <1 mV/m ECH emissions throughout the outer magnetosphere (L > 5). The strongest (>=1 mV/m) ECH waves are enhanced during geomagnetically disturbed periods, and are mainly confined close to the magnetic equator (|lambda| < 3°) over the region L <= 10 in the night and dawn MLT sector. ECH wave intensities within 3° <= |lambda| < 6° are generally much weaker but not negligible especially for L < 12 on the midnight side. Furthermore, the occurrence rates and variability of moderately intense (>=0.1 mV/m) ECH emissions suggest that ECH wave scattering could contribute to diffuse auroral precipitation in the outer (L > 8) magnetosphere where chorus emissions are statistically weak. (10.1029/2011GL048793)
  DOI : 10.1029/2011GL048793
• Plasmoid Releases in the Heliospheric Current Sheet and Associated Coronal Hole Boundary Layer Evolution
  
  • Foullon C.
  • Lavraud B.
  • Luhmann J. G.
  • Farrugia C. J.
  • Retinò Alessandro
  • Simunac K. D. C.
  • Wardle N. C.
  • Galvin A. B.
  • Kucharek H.
  • Owen C. J.
  • Popecki M.
  • Opitz A.
  • Sauvaud J.-A.
  The Astrophysical Journal, American Astronomical Society, 2011, 737, pp.16. As the heliospheric current sheet (HCS) is corotating past STEREO-B, near-Earth spacecraft ACE, Wind and Cluster, and STEREO-A over more than three days between 2008 January 10 and 14, we observe various sections of (near-pressure-balanced) flux-rope- and magnetic-island-type plasmoids in the associated heliospheric plasma sheet (HPS). The plasmoids can qualify as slow interplanetary coronal mass ejections and are relatively low proton beta (<0.5) structures, with small length scales (an order of magnitude lower than typical magnetic cloud values) and low magnetic field strengths (2-8 nT). One of them, in particular, detected at STEREO-B, corresponds to the first reported evidence of a detached plasmoid in the HPS. The in situ signatures near Earth are associated with a long-decay X-ray flare and a slow small-scale streamer ejecta, observed remotely with white-light coronagraphs aboard STEREO-B and SOHO and tracked by triangulation. Before the arrival of the HPS, a coronal hole boundary layer (CHBL) is detected in situ. The multi-spacecraft observations indicate a CHBL stream corotating with the HCS but with a decreasing speed distribution suggestive of a localized or transient nature. While we may reasonably assume that an interaction between ejecta and CHBL provides the source of momentum for the slow ejecta's acceleration, the outstanding composition properties of the CHBL near Earth provide here circumstantial evidence that this interaction or possibly an earlier one, taking place during streamer swelling when the ejecta rises slowly, results in additional mixing processes. (10.1088/0004-637X/737/1/16)
  DOI : 10.1088/0004-637X/737/1/16
• Space Exploration Technologies Pegases A new promising electric propulsion concept
  
  • Aanesland Ane
  • Mazouffre S.
  • Chabert Pascal
  Europhysics News, EDP Sciences, 2011, 42 (6), pp.28-31. This article has no abstract (10.1051/epn/2011604)
  DOI : 10.1051/epn/2011604
• Solar wind, mass and momentum losses during the solar cycle
  
  • Pinto Rui
  • Brun Allan Sacha
  • Jouve Laurène
  • Grappin Roland
  , 2011, 271 (2010-06-21 / 2010-06-25), pp.395-396. We study the connections between the sun's convection zone evolution and the dynamics of the solar wind and corona. We input the magnetic fields generated by a 2.5D axisymmetric kinematic dynamo code (STELEM) into a 2.5D axisymmetric coronal MHD code (DIP). The computations were carried out for an 11 year cycle. We show that the solar wind's velocity and mass flux vary in latitude and in time in good agreement with the well known time-latitude assymptotic wind speed diagram. Overall sun's mass loss rate, momentum flux and magnetic breaking torque are maximal near the solar minimum. (10.1017/S1743921311017960)
  DOI : 10.1017/S1743921311017960
• Impact of collisionality on fluctuation characteristics of micro-turbulence
  
  • Vermare Laure
  • Hennequin Pascale
  • Gürcan Özgür D.
  • Bourdelle C.
  • Clairet F.
  • Garbet X.
  • Sabot R.
  • Tore Supra Team
  Physics of Plasmas, American Institute of Physics, 2011, 18, pp.012306. The influence of changing collisionality on density fluctuation characteristics is studied during dedicated &#957;&#8727; scaling experiments, using Doppler backscattering system. First, the repartition of fluctuation energy over different spatial scales, as represented by the wavenumber spectrum, is investigated and a modification of the shape of the perpendicular wavenumber spectrum in the low wavenumber part of the spectrum is observed when changing collisionality. In addition, a new procedure to evaluate the dispersion relation of micro-turbulence is presented. From the behavior of the perpendicular mean velocity of density fluctuations with the perpendicular wavenumber, different dispersion relations are obtained between low and high collisionality cases. (10.1063/1.3536648)
  DOI : 10.1063/1.3536648
• Observational evidence of the generation mechanism for rising-tone chorus
  
  • Cully C. M.
  • Angelopoulos V.
  • Auster U.
  • Bonnell J. W.
  • Le Contel Olivier
  Geophysical Research Letters, American Geophysical Union, 2011, 38, pp.1106. Chorus emissions are a striking feature of the electromagnetic wave environment in the Earth's magnetosphere. These bursts of whistler-mode waves exhibit characteristic frequency sweeps (chirps) believed to result from wave-particle trapping of cyclotron-resonant particles. Based on the theory of Omura et al. (2008), we predict the sweep rates of chorus elements observed by the THEMIS satellites. The predictions use independent observations of the electron distribution functions and have no free parameters. The predicted chirp rates are a function of wave amplitude, and this relation is clearly observed. The predictive success of the theory lends strong support to its underlying physical mechanism: cyclotron-resonant wave-particle trapping. (10.1029/2010GL045793)
  DOI : 10.1029/2010GL045793
• A model of electromagnetic electron phase-space holes and its application
  
  • Tao J. B.
  • Ergun R. E.
  • Andersson L.
  • Bonnell J. W.
  • Roux A.
  • Le Contel Olivier
  • Angelopoulos V.
  • Mcfadden J. P.
  • Larson D. E.
  • Cully C. M.
  • Auster H.-U.
  • Glassmeier K.-H.
  • Baumjohann W.
  • Newman D. L.
  • Goldman M. V.
  Journal of Geophysical Research Space Physics, American Geophysical Union/Wiley, 2011, 116, pp.11213. Electron phase-space holes (EHs) are indicators of nonlinear activities in space plasmas. Most often they are observed as electrostatic signals, but recently Andersson et al. [2009] reported electromagnetic EHs observed by the THEMIS mission in the Earth's plasma sheet. As a follow-up to Andersson et al. [2009], this paper presents a model of electromagnetic EHs where the deltaE × B<SUB>0</SUB> drift of electrons creates a net current. The model is examined with test-particle simulations and compared to the electromagnetic EHs reported by Andersson et al. [2009]. As an application of the model, we introduce a more accurate method than the simplified Lorentz transformation of Andersson et al. [2009] to derive EH velocity (v<SUB>EH</SUB>). The sizes and potentials of EHs are derived from v<SUB>EH</SUB>, so an accurate derivation of v<SUB>EH</SUB> is important in analyzing EHs. In general, our results are qualitatively consistent with those of Andersson et al. [2009] but generally with smaller velocities and sizes. (10.1029/2010JA016054)
  DOI : 10.1029/2010JA016054
• On the effect of IMF turning on ion dynamics at Mercury
  
  • Delcourt Dominique C.
  • Moore T. E.
  • Fok M.-C. H.
  Annales Geophysicae, European Geosciences Union, 2011, 29, pp.987-996. We investigate the effect of a rotation of the Interplanetary Magnetic Field (IMF) on the transport of magnetospheric ion populations at Mercury. We focus on ions of planetary origin and investigate their large-scale circulation using three-dimensional single-particle simulations. We show that a nonzero B<SUB>X</SUB> component of the IMF leads to a pronounced asymmetry in the overall circulation pattern. In particular, we demonstrate that the centrifugal acceleration due to curvature of the E × B drift paths is more pronounced in one hemisphere than the other, leading to filling of the magnetospheric lobes and plasma sheet with more or less energetic material depending upon the hemisphere of origin. Using a time-varying electric and magnetic field model, we investigate the response of ions to rapid (a few tens of seconds) re-orientation of the IMF. We show that, for ions with gyroperiods comparable to the field variation time scale, the inductive electric field should lead to significant nonadiabatic energization, up to several hundreds of eVs or a few keVs. It thus appears that IMF turning at Mercury should lead to localized loading of the magnetosphere with energetic material of planetary origin (e.g., Na<SUP> </SUP>). (10.5194/angeo-29-987-2011)
  DOI : 10.5194/angeo-29-987-2011
• Estimation of magnetic field mapping accuracy using the pulsating aurora-chorus connection
  
  • Nishimura Y.
  • Bortnik J.
  • Li W.
  • Thorne R. M.
  • Lyons L.R.
  • Angelopoulos V.
  • Mende S. B.
  • Bonnell J. W.
  • Le Contel Olivier
  • Cully C. M.
  • Ergun R.
  • Auster U.
  Geophysical Research Letters, American Geophysical Union, 2011, 38, pp.14110. Although magnetic field models are widely used in magnetosphere-ionosphere coupling studies to perform field-line mapping, their accuracy has been difficult to estimate experimentally. Taking advantage of the high correlation between lower-band chorus and pulsating aurora, we located the THEMIS spacecraft footprint within km accuracy and calculated the differences from mappings given in widely-used Tsyganenko models. Using 13 conjunctions of the THEMIS spacecraft and ground-based imagers, we found that the Tsyganenko model footprints were located within 1°-2° magnetic latitude and 0.1-0.2 h magnetic local time of our derived footprint. The deviation between the footprints has a consistent dependence on geomagnetic activity. Our results showed that the real magnetic field tends to be less stretched than that in the Tsyganenko models during quiet times and comparable to or more stretched during disturbed times. This approach can be used to advance modeling of field lines that connect to the near-Earth plasma sheet. (10.1029/2011GL048281)
  DOI : 10.1029/2011GL048281
• Polar cap ion beams during periods of northward IMF: Cluster statistical results
  
  • Maggiolo R.
  • Echim M.
  • de Keyser J.
  • Fontaine Dominique
  • Jacquey C.
  • Dandouras I.
  Annales Geophysicae, European Geosciences Union, 2011, 29, pp.771-787. Above the polar caps and during prolonged periods of northward IMF, the Cluster satellites detect upward accelerated ion beams with energies up to a few keV. They are associated with converging electric field structures indicating that the acceleration is caused by a quasi-static field-aligned electric field that can extend to altitudes higher than 7 R<SUB>E</SUB> (Maggiolo et al., 2006; Teste et al., 2007). Using the AMDA science analysis service provided by the Centre de Données de la Physique des Plasmas, we have been able to extract about 200 events of accelerated upgoing ion beams above the polar caps from the Cluster database. Most of these observations are taken at altitudes lower than 7 R<SUB>E</SUB> and in the Northern Hemisphere. We investigate the statistical properties of these ion beams. We analyze their geometry, the properties of the plasma populations and of the electric field inside and around the beams, as well as their dependence on solar wind and IMF conditions. We show that ~40 % of the ion beams are collocated with a relatively hot and isotropic plasma population. The density and temperature of the isotropic population are highly variable but suggest that this plasma originates from the plasma sheet. The ion beam properties do not change significantly when the isotropic, hot background population is present. Furthermore, during one single polar cap crossing by Cluster it is possible to detect upgoing ion beams both with and without an accompanying isotropic component. The analysis of the variation of the IMF B<SUB>Z</SUB> component prior to the detection of the beams indicates that the delay between a northward/southward turning of IMF and the appearance/disappearance of the beams is respectively ~2 h and 20 min. The observed electrodynamic characteristics of high altitude polar cap ion beams suggest that they are closely connected to polar cap auroral arcs. We discuss the implications of these Cluster observations above the polar cap on the magnetospheric dynamics and configuration during prolonged periods of northward IMF. (10.5194/angeo-29-771-2011)
  DOI : 10.5194/angeo-29-771-2011
• Two-Temperature Models for Polar Plumes: Cooling by Means of Strong Base Heating
  
  • Grappin Roland
  • Wang Y-M
  • Pantellini F.
  The Astrophysical Journal, American Astronomical Society, 2011, 727 (1), pp.30. In earlier one-fluid hydrodynamical calculations incorporating heat conduction and radiative losses, it was shown that the high densities in polar plumes could be reproduced by including a concentrated heat source near the plume base, in addition to the global heating required in both the plume and interplume regions of the coronal hole. The extra heating (attributed to interchange reconnection between the open flux and an underlying magnetic bipole) results in lower flow speeds and temperatures relative to the interplume gas, predictions that have since been confirmed by spectroscopic measurements. Here, the model is extended to the two-fluid case, in which ions and electrons are allowed to have different temperatures, coupling is via Coulomb collisions, and heat transport is mainly by electrons. Again, we find that depositing energy very close to the coronal base, in either the protons or electrons (or both), raises the densities and decreases the flow speeds everywhere along the flux tube. The higher densities in turn act to lower the ion temperatures by coupling the protons more closely to the energy-losing electrons. In addition, we find that energy must be deposited globally in both the electrons and the ions; without this direct heating, the electrons would end up cooler in the interplume region than in the plume, contrary to observations. Increasing the rate of flux-tube expansion has the effect of lowering the electron and ion temperatures and reducing the asymptotic flow speed, both in the plume and the interplume region; the observed densities and temperatures can be matched by taking the magnetic field to fall off with radius roughly as r 4. (10.1088/0004-637X/727/1/30)
  DOI : 10.1088/0004-637X/727/1/30
• Jet front-driven mirror modes and shocklets in the near-Earth flow-braking region
  
  • Zieger B.
  • Retinò Alessandro
  • Nakamura R.
  • Baumjohann W.
  • Vaivads A.
  • Khotyaintsev Y. V.
  Geophysical Research Letters, American Geophysical Union, 2011, 38, pp.22103. We investigate the small-scale structure of jet fronts through a case study of multi-spacecraft Cluster observations in the near-Earth flow-braking region at -10 RE. We find that the interaction between the earthward moving fast plasma jet and the high-&#946; ambient plasma in the plasma sheet results in magnetic pileup and compression ahead of the jet and rarefaction trailing the jet. It is shown that mirror-mode structures of ion gyroradius scale develop within the pileup region due to the observed ion temperature anisotropy (Ti⊥ > Ti\parallel). We suggest that the growth of these mirror modes is driven by the perpendicular total pressure perturbation (&#916;p⊥) generated by the braking jet. When &#916;p⊥ becomes too large, the mirror-mode structure cannot maintain pressure balance any longer, and consequently a shocklet is formed in the pileup region ahead of the jet front. We present the first evidence for such a kinetic shocklet in the flow-braking region. (10.1029/2011GL049746)
  DOI : 10.1029/2011GL049746
• Different regimes of MHD turbulence with mean magnetic field
  
  • Grappin Roland
  , 2011.
• A new 3D parallel multi-species hybrid model for Solar Wind - Mars interaction
  
  • Hess Sebastien
  • Modolo Ronan
  • Mancini Marco
  • Leblanc François
  • Chaufray Jean-Yves
  • Yagi Manabu
  • Allioux R.
  • Richer Emilie
  • Chanteur Gérard
  , 2011, pp.EPSC-DPS2011-770. In the frame of the HELIOSARES project (PI F. Leblanc) dedicated to the modeling of Mars environment (neutral and charged species) from the lower atmosphere to the solar wind, a modeling effort of parallelization has been conducted. Such model allows having a kinetic description of the ions with a rather improved spatial resolution (smaller than the ion inertial less). The latest progresses are reported and simulations results with a uniform spatial resolution of 75 km are presented.
• AC magnetic field measurements onboard Cross-Scale: scientific objectives and instrument design
  
  • Dudok de Wit Thierry
  • Coillot Christophe
  • Jannet Guillaume
  • Krasnoselskikh V.
  • Kretzschmar Matthieu
  • Pinçon Jean-Louis
  • Sahraoui Fouad
  Planetary and Space Science, Elsevier, 2011, 59 (7), pp.580-584. The ACB search-coil magnetometer for Cross-Scale will measure three components of the AC magnetic field up to 4 kHz, and one component up to 100 kHz. Turbulent and coherent magnetic field fluctuations in that frequency range play an important role in the acceleration, scattering, and thermalisation of particles. ACB will, together with the other instruments of the Cross-Scale wave consortium, allow to address the key science objectives associated with plasma waves. Here, we list some of the important issues, based on the experience drawn from Cluster, and describe the instrument. (10.1016/j.pss.2010.04.022)
  DOI : 10.1016/j.pss.2010.04.022
• Role of charge photodesorption in self-synchronized breakdown of surface streamers in air at atmospheric pressure
  
  • Guaitella Olivier
  • Marinov Ilya
  • Rousseau Antoine
  Applied Physics Letters, American Institute of Physics, 2011, 98, pp.071502. A surface dielectric barrier discharge configuration with two identical high voltage electrodes is investigated in air at atmospheric pressure. Synchronized breakdown of streamers on both electrodes is evidenced by statistical study. The light emitted by plasma filament on one electrode can trigger the breakdown of streamers on the other electrode. The role of photodesorption of negative charges deposited on the Pyrex dielectric barrier is responsible for these self-synchronized breakdowns. The binding energy of negative charges photodesorbed is estimated to be lower than 3.5 eV. (10.1063/1.3552965)
  DOI : 10.1063/1.3552965
• NO kinetics in pulsed low-pressure plasmas studied by time-resolved quantum cascade laser absorption spectroscopy
  
  • Welzel S.
  • Guaitella Olivier
  • Lazzaroni Claudia
  • Pintassilgo C.D.
  • Rousseau Antoine
  • Röpcke J.
  Plasma Sources Science and Technology, IOP Publishing, 2011, 20, pp.015020. Time-resolved quantum cascade laser absorption spectroscopy at 1897&#8201;cm&#8722;1 (5.27&#8201;µm) has been applied to study the NO(X) kinetics on the micro- and millisecond time scale in pulsed low-pressure N2/NO dc discharges. Experiments have been performed under flowing and static gas conditions to infer the gas temperature increase and the consequences for the NO line strength. A relatively small increase of ~20&#8201;K is observed during the early plasma phase of a few milliseconds. After some 10&#8201;ms gas temperatures up to 500&#8201;K can be deduced. The experimental data for the NO mixing ratio were compared with the results from a recently developed time-dependent model for pulsed N2O2 plasmas which are well in accord. The early plasma pulse is determined by vibrational heating of N2 while the excitation of NO(X) by N2 metastables is almost completely balanced. Efficient NO depletion occurs after several milliseconds by N atom impact. (10.1088/0963-0252/20/1/015020)
  DOI : 10.1088/0963-0252/20/1/015020
• Observations and modeling of forward and reflected chorus waves captured by THEMIS
  
  • Agapitov O
  • Krasnoselskikh V
  • Zaliznyak Yu
  • Angelopoulos V
  • Le Contel Olivier
  • Rolland G
  Annales Geophysicae, European Geosciences Union, 2011, 29, pp.541-550. Discrete ELF/VLF chorus emissions are the most intense electromagnetic plasma waves observed in the radiation belts of the Earth's magnetosphere. Chorus emissions, whistler-mode wave packets propagating roughly along magnetic field lines from a well-localized source in the vicinity of the magnetic equator to polar regions, can be reflected at low altitudes. After reflection, wave packets can return to the equatorial plane region. Understanding of whistler wave propagation and reflection is critical to a correct description of wave-particle interaction in the radiation belts. We focus on properties of reflected chorus emissions observed by the THEMIS (Time History of Events and Macroscale Interactions During Substorms) spacecraft Search Coil Magnetome-ter (SCM) and Electric Field Instrument (EFI) at ELF/VLF frequencies up to 4 kHz at L ≥ 8. We determine the direction of the Poynting flux and wave vector distribution for forward and reflected chorus waves. Although both types of chorus waves were detected near the magnetic equator and have similar , discrete structure and rising tones, reflected waves are attenuated by a factor of 10–30 and have 10% higher frequency than concurrently-observed forward waves. Model-ing of wave propagation and reflection using geometrical optics ray-tracing allowed us to determine the chorus source region location and explain observed propagation characteristics. We find that reflected wave attenuation at a certain spatial region is caused by divergence of the ray paths of these non-ducted emissions, and that the frequency shift is caused by generation of the reflected waves at lower L-shells where the local equatorial gyrofrequency is larger. (10.5194/angeo-29-541-2011)
  DOI : 10.5194/angeo-29-541-2011
• Anisotropic shell model of turbulence
  
  • Gürcan Özgür D.
  • Grappin Roland
  Physical Review E, American Physical Society (APS), 2011, 84, pp.066308. An anisotropic shell model has been proposed for two-dimensional (2D) turbulence. It is similar to the 2D version of the Gledzer-Ohkitani-Yamada model but with the angular variable in wave-number space divided into three distinct directions representing structures elongated in different directions. In the case when the drive is isotropic the usual isotropic solution is recovered as the fixed point of this model. The Hasegawa-Mima limit of the model is considered in particular due to its relevance for 2D anisotropic systems such a quasigeostrophic and plasma turbulence. It is observed from this simple model that the anisotropy diminishes as a function of scale during the cascade process, and the maximum of the energy is not at the node that has maximum drive, but at a nearby node that is directly coupled to that one. (10.1103/PhysRevE.84.066308)
  DOI : 10.1103/PhysRevE.84.066308
• A global model of micro-hollow cathode discharges in the stationary regime
  
  • Lazzaroni Claudia
  • Chabert Pascal
  Journal of Physics D: Applied Physics, IOP Publishing, 2011, 44, pp.445202. This paper presents a global model of micro-hollow cathode discharges working in argon gas. Inspired by experiments and two-dimensional numerical simulations, the discharge is decomposed into two main regions, labelled the cathodic region and the positive column region. The first is composed of a cathode sheath (surrounding the cathode) and a plasma in the centre, while the positive column region is essentially filled with plasma. A cathode sheath model is developed to calculate the sheath size and the power dissipated by ions and electrons in the sheath. Charged-particle transport equations are solved in one-dimensional cylindrical coordinates, in the quasi-neutral plasma region, in order to determine the radial density profiles and the electron temperature in the microhole. A global power balance is then performed in the two distinct regions in order to determine the absolute electron density. We found that the electron density is one order of magnitude higher in the cathodic region than in the positive column, showing that the power dissipation is mainly located in the cathode sheath. The calculated electron density in the cathodic region is in reasonable agreement with experiments. (10.1088/0022-3727/44/44/445202)
  DOI : 10.1088/0022-3727/44/44/445202