Turbulent Magnetic Reconnection in Two Dimensions (2009)
Loureiro, N. F., Uzdensky, D. A., Schekochihin, A. A., Cowley, S. C., Yousef, T. A.
Two-dimensional numerical simulations of the effect of background turbulence on 2D resistive magnetic reconnection are presented. For sufficiently small values of the resistivity ($\eta$) and...
Two dimensional magnetised plasma turbulence (2009)
Plunk, G. G., Cowley, S. C., Schekochihin, A. A., Tatsuno, T.
Two dimensional gyrokinetics is a simple paradigm for the study of kinetic magnetised turbulence. In this paper, we study both the inverse and direct cascades (i.e., the `dual cascade'), driven by a...
Formation of Plasmoid Chains in Magnetic Reconnection (2009)
Samtaney, R., Loureiro, N. F., Uzdensky, D. A., Schekochihin, A. A., Cowley, S. C.
A detailed numerical study of magnetic reconnection in resistive MHD for very large, previously inaccessible, Lundquist numbers ($10^4\le S\le 10^8$) is reported. Large-aspect-ratio Sweet-Parker...
Howes, G. G., Cowley, S. C., Dorland, W., Hammett, G. W., Quataert, E., Schekochihin, A. A., ...
Howes et al. Reply to Comment on "Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas" arXiv:0711.4355
Nonlinear phase mixing and phase-space cascade of entropy in gyrokinetic plasma turbulence (2008)
Tatsuno, T., Dorland, W., Schekochihin, A. A., Plunk, G. G., Barnes, M., Cowley, S. C., ...
Electrostatic turbulence in weakly collisional, magnetized plasma can be interpreted as a cascade of entropy in phase space. This cascade is studied theoretically and numerically. It proceeds...
Linearized model Fokker-Planck collision operators for gyrokinetic simulations. I. Theory (2008)
Abel, I. G., Barnes, M., Cowley, S. C., Dorland, W., Schekochihin, A. A.
A new analytically and numerically manageable model collision operator is developed specifically for turbulence simulations. The like-particle collision operator includes both pitch-angle scattering...
Numerical experiments on dynamo action in sheared and rotating turbulence (2008)
Yousef, T. A., Heinemann, T., Rincon, F., Schekochihin, A. A., Kleeorin, N., Rogachevskii, I., ...
Numerical simulations of forced turbulence in elongated shearing boxes are carried out to demonstrate that a nonhelical turbulence in conjunction with a linear shear can give rise to a mean-field...
Gyrokinetic turbulence: a nonlinear route to dissipation through phase space (2008)
Schekochihin, A. A., Cowley, S. C., Dorland, W., Hammett, G. W., Howes, G. G., Plunk, G. G., ...
This paper describes a conceptual framework for understanding kinetic plasma turbulence as a generalized form of energy cascade in phase space. It is emphasized that conversion of turbulent energy...
Dual equilibrium in a finite aspect ratio tokamak (2008)
A new approach to high pressure magnetically-confined plasmas is necessary to design efficient fusion devices. This paper presents an equilibrium combining two solutions of the Grad-Shafranov...
Kinetic Simulations of Magnetized Turbulence in Astrophysical Plasmas (2007)
Howes, G. G., Dorland, W., Cowley, S. C., Hammett, G. W., Quataert, E., Schekochihin, A. A., ...
This letter presents the first ab initio, fully electromagnetic, kinetic simulations of magnetized turbulence in a homogeneous, weakly collisional plasma at the scale of the ion Larmor radius (ion...
Generation of Magnetic Field by Combined Action of Turbulence and Shear (2007)
Yousef, T. A., Heinemann, T., Schekochihin, A. A., Kleeorin, N., Rogachevskii, I., Iskakov, A. B., ...
The feasibility of a mean-field dynamo in nonhelical turbulence with superimposed linear shear is studied numerically in elongated shearing boxes. Exponential growth of magnetic field at scales much...
Nonlinear growth of firehose and mirror fluctuations in turbulent galaxy-cluster plasmas (2007)
Schekochihin, A. A., Cowley, S. C., Kulsrud, R. M., Rosin, M. S., Heinemann, T.
In turbulent high-beta astrophysical plasmas (exemplified by the galaxy cluster plasmas), pressure-anisotropy-driven firehose and mirror fluctuations grow nonlinearly to large amplitudes, dB/B ~ 1,...
Fluctuation dynamo and turbulent induction at low magnetic Prandtl numbers (2007)
Schekochihin, A. A., Iskakov, A. B., Cowley, S. C., McWilliams, J. C., Proctor, M. R. E., Yousef, T. A.
This paper is a detailed report on a programme of simulations used to settle a long-standing issue in the dynamo theory and demonstrate that the fluctuation dynamo exists in the limit of large...
Schekochihin, A. A., Cowley, S. C., Dorland, W., Hammett, G. W., Howes, G. G., Quataert, E., ...
We present a theoretical framework for plasma turbulence in astrophysical plasmas (solar wind, interstellar medium, galaxy clusters, accretion disks). The key assumptions are that the turbulence is...
Instability of current sheets and formation of plasmoid chains (2007)
Loureiro, N. F., Schekochihin, A. A., Cowley, S. C.
Current sheets formed in magnetic reconnection events are found to be unstable to high-wavenumber perturbations. The instability is very fast: its maximum growth rate scales as S^{1/4} v_A/L, where L...
Numerical demonstration of fluctuation dynamo at low magnetic Prandtl numbers (2007)
Iskakov, A. B., Schekochihin, A. A., Cowley, S. C., McWilliams, J. C., Proctor, M. R. E.
Direct numerical simulations of incompressible nonhelical randomly forced MHD turbulence are used to demonstrate for the first time that the fluctuation dynamo exists in the limit of large magnetic...
Gyrokinetic simulations of ETG and ITG turbulence (2007)
Dimits, A. M., Nevins, W. M., Shumaker, D. E., Hammett, G. W., Dannert, T., Jenko, F., ...
Interplanetary and interstellar plasma turbulence (2006)
Schekochihin, A. A., Cowley, S. C., Dorland, W.
Theoretical approaches to low-frequency magnetized turbulence in collisionless and weakly collisional astrophysical plasmas are reviewed. The proper starting point for an analytical description of...
Turbulence, magnetic fields and plasma physics in clusters of galaxies (2006)
Schekochihin, A. A., Cowley, S. C.
Observations of galaxy clusters show that the intracluster medium (ICM) is likely to be turbulent and is certainly magnetized. The properties of this magnetized turbulence are determined both by...
Fast growth of magnetic fields in galaxy clusters: a self-accelerating dynamo (2005)
Schekochihin, A. A., Cowley, S. C.
We propose a model of magnetic-field growth in galaxy clusters whereby the field is amplified by a factor of about 10^8 over a cosmologically short time of ~10^8 yr. Our model is based on the idea...
Turbulence and Magnetic Fields in Astrophysical Plasmas (2005)
Schekochihin, A. A., Cowley, S. C.
We discuss the current understanding of the most basic properties of astrophysical MHD turbulence and trace the origins of the modern views and theoretical uncertainties to the ideas set forth in...
X-point collapse and saturation in the nonlinear tearing mode reconnection (2005)
Loureiro, N. F., Cowley, S. C., Dorland, W. D., Haines, M. G., Schekochihin, A. A.
We study the nonlinear evolution of the resistive tearing mode in slab geometry in two dimensions. We show that, in the strongly driven regime (large Delta'), a collapse of the X-point occurs once...
Plasma instabilities and magnetic-field growth in clusters of galaxies (2005)
Schekochihin, A. A., Cowley, S. C., Kulsrud, R. M., Hammett, G. W., Sharma, P.
We show that under very general conditions, cluster plasmas threaded by weak magnetic fields are subject to very fast growing plasma instabilities driven by the anisotropy of the plasma pressure...
The onset of a small-scale turbulent dynamo at low magnetic Prandtl numbers (2004)
Schekochihin, A. A., Haugen, N. E. L., Brandenburg, A., Cowley, S. C., Maron, J. L., McWilliams, J. C.
We study numerically the dependence of the critical magnetic Reynolds number Rmc for the turbulent small-scale dynamo on the hydrodynamic Reynolds number Re. The turbulence is statistically...
Magnetised plasma turbulence in clusters of galaxies (2004)
Schekochihin, A. A., Cowley, S. C., Kulsrud, R. M., Hammett, G. W., Sharma, P.
Cluster plasmas are magnetised already at very low magnetic field strength. Low collisionality implies that conservation of the first adiabatic invariant results in an anisotropic viscous stress...
Fast and slow nonlinear tearing mode reconnection (2004)
Loureiro, N. F., Cowley, S. C., Dorland, W. D., Haines, M. G., Schekochihin, A. A.
This is a brief account of our numerical study of the tearing mode reconnection. We demonstrate two main points. First, we show that, given sufficiently small resistivity, the Rutherford regime...
Diffusion of passive scalar in a finite-scale random flow (2004)
Schekochihin, A. A., Haynes, P. H., Cowley, S. C.
We consider a solvable model of the decay of scalar variance in a single-scale random velocity field. We show that if there is a separation between the flow scale k_flow^{-1} and the box size...
Theory for Explosive Ideal Magnetohydrodynamic Instabilities in Plasmas (2004)
Flux tubes confined in tokamaks are observed to erupt explosively in some plasma disruptions and edge localized modes. Similar eruptions occur in astrophysical plasmas, for example, in solar flares...
Spatial and Temporal Structure of Edge-Localized Modes (2004)
Kirk, A., Wilson, H.R., Counsell, G.F., Akers, R., Arends, E., Cowley, S.C., ...
This Letter provides information on the spatial and temporal structure of periodic eruptions observed in magnetically confined laboratory fusion plasmas, called edge-localized modes (ELMs), and...
Simulations of small-scale turbulent dynamo (2003)
Schekochihin, A. A., Cowley, S. C., Taylor, S. F., Maron, J. L., McWilliams, J. C.
We report an extensive numerical study of the small-scale turbulent dynamo at large magnetic Prandtl numbers Pm. A Pm scan is given for the model case of low-Reynolds-number turbulence. We...
Critical Magnetic Prandtl Number for Small-Scale Dynamo (2003)
Schekochihin, A. A., Cowley, S. C., Maron, J. L., McWilliams, J. C.
We report a series of numerical simulations showing that the critical magnetic Reynolds number Rm_c for the nonhelical small-scale dynamo depends on the Reynolds number Re. Namely, the dynamo is shut...
Saturated State of the Nonlinear Small-Scale Dynamo (2003)
Schekochihin, A. A., Cowley, S. C., Taylor, S. F., Hammett, G. W., Maron, J. L., McWilliams, J. C.
We consider the problem of incompressible, forced, nonhelical, homogeneous and isotropic MHD turbulence with no mean magnetic field and large magnetic Prandtl number. This type of MHD turbulence is...
Self-similar turbulent dynamo (2003)
Schekochihin, A. A., Cowley, S. C., Maron, J. L., McWilliams, J. C.
The amplification of magnetic fields in a highly conducting fluid is studied numerically. During growth, the magnetic field is spatially intermittent: it does not uniformly fill the volume, but is...
From Small-Scale Dynamo to Isotropic MHD Turbulence (2003)
Schekochihin, A. A., Cowley, S. C., Taylor, S. F., Maron, J. L., McWilliams, J. C.
We consider the problem of incompressible, forced, nonhelical, homogeneous, isotropic MHD turbulence with no mean magnetic field. This problem is essentially different from the case with externally...
A model of nonlinear evolution and saturation of the turbulent MHD dynamo (2002)
Schekochihin, A. A., Cowley, S. C., Hammett, G. W., Maron, J. L., McWilliams, J. C.
The growth and saturation of magnetic field in conducting turbulent media with large magnetic Prandtl numbers are investigated. This regime is very common in low-density hot astrophysical plasmas....
The nonlinear small-scale dynamo and isotropic MHD turbulence (2002)
Schekochihin, A. A., Cowley, S. C., Hammett, G. W., Maron, J. L., McWilliams, J. C.
This is a brief review of the main results of our recent studies of the nonlinear evolution of the small-scale MHD dynamo in the high-Prandtl-number regime and of the structure of the resulting...
M. A. Beer, S. C. Cowley, G. W. Hammett
Turbulence in tokamaks is characterized by long parallel wavelengths and short perpendicular wavelengths. A coordinate system for nonlinear fluid, gyrokinetic "Vlasov, " or particle...
McDonald, M K, Cowley, S C, Nano, F E
The valAB locus of Francisella novicida has previously been found to be highly similar at the deduced amino acid level to msbA lpxK of Escherichia coli. Both ValA and MsbA are members of the...
McDonald, M K, Cowley, S C, Nano, F E
The valAB locus of Francisella novicida has previously been found to be highly similar at the deduced amino acid level to msbA lpxK of Escherichia coli. Both ValA and MsbA are members of the...