Browsing by Subject "Plasmas"

Now showing items 1-20 of 23

  • 3D PiC code investigations of Auroral Kilometric Radiation mechanisms 

    Gillespie, K. M.; McConville, S. L.; Speirs, D. C.; Ronald, K.; Phelps, A. D. R.; Bingham, R.; Cross, A. W.; Robertson, C. W.; Whyte, C. G.; He, W.; Vorgul, I.; Cairns, R. A.; Kellett, B. J. (IOP Publishing Ltd., 2014) - Conference item
    Efficient (similar to 1%) electron cyclotron radio emissions are known to originate in the X mode from regions of locally depleted plasma in the Earths polar magnetosphere. These emissions are commonly referred to as the ...

  • 3D pic simulations of collisionless shocks at lunar magnetic anomalies and their role in forming lunar swirls 

    Bamford, R. A.; Alves, E. P.; Cruz, F.; Kellett, B. J.; Fonsesca, R. A.; Silva, L. O.; Trines, R. M. G. M.; Halekas, J. S.; Kamer, G.; Harnett, E.; Cairns, Robert Alan; Bingham, R. (2016-10-18) - Journal article
    Investigation of the lunar crustal magnetic anomalies offers a comprehensive long-term data set of observations of small-scale magnetic fields and their interaction with the solar wind. In this paper a review of the ...

  • Alfven wave phase-mixing and damping in the ion cyclotron range of frequencies 

    Threlfall, J.; McClements, K. G.; De Moortel, I. (2011-01) - Journal article
    Aims. We determine the effect of the Hall term in the generalised Ohm's law on the damping and phase mixing of Alfven waves in the ion cyclotron range of frequencies in uniform and non-uniform equilibrium plasmas. Methods. ...

  • Coronal heating by the partial relaxation of twisted loops 

    Bareford, Michael; Hood, Alan; Browning, Philippa (2013-02) - Journal article
    Context: Relaxation theory offers a straightforward method for estimating the energy that is released when a magnetic field becomes unstable, as a result of continual convective driving. Aims: We present new results obtained ...

  • The detection of numerous magnetic separators in a three-dimensional magnetohydrodynamic model of solar emerging flux 

    Parnell, Clare Elizabeth; Maclean, Rhona Claire; Haynes, Andrew Lewis (2010-12-20) - Journal item
    Magnetic separators in three-dimensional (3D) magnetic fields are believed to be often associated with locations of magnetic reconnection. In this preliminary study, we investigate this relationship using data from a ...

  • Electrostatic activation of prebiotic chemistry in substellar atmospheres 

    Stark, Craig Ronald; Helling, Christiane; Diver, Declan A; Rimmer, Paul (2014-04) - Journal article
    Charged dust grains in the atmospheres of exoplanets may play a key role in the formation of prebiotic molecules, necessary to the origin of life. Dust grains submerged in an atmospheric plasma become negatively charged ...

  • Evolution of field line helicity during magnetic reconnection 

    Russell, A. J. B.; Yeates, A. R.; Hornig, G.; Wilmot-Smith, A. L. (2015-03) - Journal article
    We investigate the evolution of field line helicity for magnetic fields that connect two boundaries without null points, with emphasis on localized finite-B magnetic reconnection. Total ( relative) magnetic helicity is ...

  • First comparison of wave observations from CoMP and AIA/SDO 

    Threlfall, James William; De Moortel, Ineke; McIntosh, Scott; Bethge, Christian (2013-08) - Journal article
    Context. Waves have long been thought to contribute to the heating of the solar corona and the generation of the solar wind. Recent observations have demonstrated evidence of quasi-periodic longitudinal disturbances and ...

  • Inference of heating properties from "hot" non-flaring plasmas in active region cores. I. Single nanoflares 

    Barnes, W. T.; Cargill, P. J.; Bradshaw, S. J. (2016-09-20) - Journal article
    The properties that are expected of “hot” non-flaring plasmas due to nanoflare heating in active regions are investigated using hydrodynamic modeling tools, including a two-fluid development of the Enthalpy Based Thermal ...

  • Inference of heating properties from "hot" non-flaring plasmas in active region cores. II. Nanoflare trains 

    Barnes, W. T.; Cargill, P. J.; Bradshaw, S. J. (2016-12-20) - Journal article
    Despite its prediction over two decades ago, the detection of faint, high-temperature ("hot") emission due to nanoflare heating in non-flaring active region cores has proved challenging. Using an efficient two-fluid ...

  • Ionization in atmospheres of brown dwarfs and extrasolar planets VI : properties of large-scale discharge events 

    Bailey, R.L.; Helling, Christiane; Hodosán, G.; Bilger, C.; Stark, C.R. (2014-03-20) - Journal article
    Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged ...

  • Ionization in atmospheres of brown dwarfs and extrasolar planets. I. The role of electron avalanche 

    Helling, Christiane; Jardine, M.; Witte, S.; Diver, D. A. (2011-01-20) - Journal article
    Brown dwarf and extrasolar planet atmospheres form clouds which strongly influence the local chemistry and physics. These clouds are globally neutral obeying dust-gas charge equilibrium which is, on short timescales, ...

  • Ionization in atmospheres of brown dwarfs and extrasolar planets. V. Alfvén ionization 

    Stark, C.R.; Helling, C.; Diver, D.A.; Rimmer, P.B. (2013-10-10) - Journal article
    Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient ...

  • Nonlinear wave propagation and reconnection at magnetic X-points in the Hall MHD regime 

    Threlfall, James William; Parnell, Clare Elizabeth; De Moortel, Ineke; McClements, Ken; Arber, Tony D. (2012-07) - Journal article
    Context: The highly dynamical, complex nature of the solar atmosphere naturally implies the presence of waves in a topologically varied magnetic environment. Here, the interaction of waves with topological features such ...

  • Particle acceleration at a reconnecting magnetic separator 

    Threlfall, J.; Neukirch, T.; Parnell, Clare Elizabeth; Eradat Oskoui, S. (2015-02) - Journal article
    While the exact acceleration mechanism of energetic particles during solar flares is (as yet) unknown, magnetic reconnection plays a key role both in the release of stored magnetic energy of the solar corona and the magnetic ...

  • Particle acceleration at reconnecting separator current layers 

    Threlfall, J.; E. H. Stevenson, J.; E. Parnell, C.; Neukirch, T. (2016) - Journal article
    The aim of this work is to investigate and characterise particle behaviour in a 3D MHD model of a reconnecting magnetic separator. We use a relativistic guiding-centre test-particle code to investigate electron and proton ...

  • Particle dynamics in a non-flaring solar active region model 

    Threlfall, J.; -A. Bourdin, Ph.; Neukirch, T.; E. Parnell, C. (2016-03) - Journal article
    The aim of this work is to investigate and characterise particle behaviour in a (observationally-driven) 3D MHD model of the solar atmosphere above a slowly evolving, non-flaring active region. We use a relativistic ...

  • Properties of the prominence magnetic field and plasma distributions as obtained from 3D whole-prominence fine structure modeling 

    Gunar, Stanislav; Mackay, Duncan Hendry (2016-08) - Journal article
    Aims. We analyze distributions of the magnetic field strength and prominence plasma (temperature, pressure, plasma beta, and mass) using the 3D whole-prominence fine structure model. Methods. The model combines a 3D magnetic ...

  • Reference study to characterize plasma and magnetic properties of ultracool atmospheres 

    Rodriguez-Barrera, Maria Isabel; Helling, Christiane; Stark, Craig Ronald; Rice, Anna (2015-12-21) - Journal article
    Radio and X-ray emission from brown dwarfs (BDs) suggest that an ionized gas and a magnetic field with a sufficient flux density must be present. We perform a reference study for late M-dwarfs (MD), BDs and giant gas planet ...

  • Solar coronal jets : observations, theory, and modeling 

    Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.; Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.; DeVore, C. R.; Archontis, V.; Török, T.; Mason, H.; Curdt, W.; Meyer, K.; Dalmasse, K.; Matsui, Y. (2016-11) - Journal article
    Coronal jets represent important manifestations of ubiquitous solar transients, which may be the source of significant mass and energy input to the upper solar atmosphere and the solar wind. While the energy involved in a ...