174 citations · 665 across the 23 of their papers we have counts for
23 papers
A tensor invariant approach to energy flux in magnetohydrodynamic turbulence
Conan M. Liptrott, Sandra C. Chapman, Bogdan Hnat +1
A scale-by-scale analysis of energy flux in the turbulent cascade can be performed using the spatially filtered magnetohydrodynamic (MHD) equations, while the gradient tensor invar…
A parallel workload has extreme variability
R. Henwood, N. W. Watkins, S. C. Chapman +1
In both high-performance computing (HPC) environments and the public cloud, the duration of time to retrieve or save your results is simultaneously unpredictable and important to y…
The global build-up to intrinsic ELM bursts seen in divertor full flux loops in Jet
S. C. Chapman, R. O. Dendy, T. N. Todd +4
A global signature of the build-up to an intrinsic ELM is found in the phase of signals measured in full flux azimuthal loops in the divertor region of JET. Full flux loop signals…
Anomalous dispersion of Lagrangian particles in local regions of turbulent flows revealed by convex hull analysis
J. Pratt, A. Busse, W. -C. Mueller +2
Local regions of anomalous particle dispersion, and intermittent events that occur in turbulent flows can greatly influence the global statistical description of the flow. These lo…
Magnetic Reconnection and Intermittent Turbulence in the Solar Wind
K. T. Osman, W. H. Matthaeus, J. T. Gosling +5
A statistical relationship between magnetic reconnection, current sheets and intermittent turbulence in the solar wind is reported for the first time using in-situ measurements fro…
Proton Kinetic Effects and Turbulent Energy Cascade Rate in the Solar Wind
Kareem T. Osman, William H. Matthaeus, Khurom H. Kiyani +2
The first observed connection between kinetic instabilities driven by proton temperature anisotropy and estimated energy cascade rates in the turbulent solar wind is reported using…
Identifying low-dimensional dynamics in Type-I edge-localised-mode processes in JET plasmas
F. A. Calderon, R. O. Dendy, S. C. Chapman +4
Edge localised mode (ELM) measurements from reproducibly similar plasmas in the Joint European Torus (JET) tokamak, which differ only in their gas puffing rate, are analysed in ter…
Identification of intermittent multi-fractal turbulence in fully kinetic simulations of magnetic reconnection
E. Leonardis, S. C. Chapman, W. Daughton +2
Recent fully nonlinear, kinetic three-dimensional simulations of magnetic reconnection [Daughton et al. 2011] evolve structures and exhibit dynamics on multiple scales, in a manner…
Robustness of predator-prey models for confinement regime transitions in fusion plasmas
H. Zhu, S. C. Chapman, R. O. Dendy
Energy transport and confinement in tokamak fusion plasmas is usually determined by the coupled nonlinear interactions of small-scale drift turbulence and larger scale coherent non…
Impact of observational uncertainties on universal scaling of MHD turbulence
G. Gogoberidze, S. C. Chapman, B. Hnat +1
Scaling exponents are the central quantitative prediction of theories of turbulence and in-situ satellite observations of the high Reynolds number solar wind flow have provided an…
Nonaxisymmetric Anisotropy of Solar Wind Turbulence as a Direct Test for the Models of Magnetohydrodynamic Tubulence
A. J. Turner, G. Gogoberidze, S. C. Chapman
Single point spacecraft observations of the turbulent solar wind flow exhibit a characteristic nonaxisymmetric anisotropy that depends sensitively on the perpendicular power spectr…
Turbulent characteristics in the intensity fluctuations of a solar quiescent prominence observed by the \textit{Hinode} Solar Optical Telescope
Ersilia Leonardis, Sandra C. Chapman, Claire Foullon
We focus on Hinode Solar Optical Telescope (SOT) calcium II H-line observations of a solar quiescent prominence (QP) that exhibits highly variable dynamics suggestive of turbulence…
Similarity Analysis of Macroecology
S. C. Chapman, N. W. Watkins, G. Rowlands +2
We perform a full similarity analysis of an idealized ecosystem using Buckingham's theorem to obtain dimensionless similarity parameters given that some (non- unique) method ex…
The scale-free texture of the fast solar wind
B. Hnat, S. C. Chapman, G. Gogoberidze +1
The higher order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically scale-by-scale for the first time. We find a single…
On the kinetic equation of linear fractional stable motion and applications to modeling the scaling of intermittent bursts
N. W. Watkins, D. Credgington, R. Sanchez +2
Levy flights and fractional Brownian motion (fBm) have become exemplars of the heavy tailed jumps and long-ranged memory widely seen in physics. Natural time series frequently comb…
Self-similar signature of the active solar corona within the inertial range of solar wind turbulence
K. Kiyani, S. C. Chapman, B. Hnat +1
We quantify the scaling of magnetic energy density in the inertial range of solar wind turbulence seen in-situ at 1AU with respect to solar activity. At solar maximum, when the cor…
Scaling collapse and structure functions: Identifying self-affinity in finite length time series
S. C. Chapman, B. Hnat, G. Rowlands +1
Empirical determination of the scaling properties and exponents of time series presents a formidable challenge in testing, and developing, a theoretical understanding of turbulence…
Scaling and a Fokker-Planck model for fluctuations in geomagnetic indices and comparison with solar wind epsilon as seen by WIND and ACE
B. Hnat, S. C. Chapman, G. Rowlands
The evolution of magnetospheric indices on temporal scales shorter than that of substorms is characterized by bursty, intermittent events that may arise from turbulence intrinsic t…
Comment on Bramwell et al, "Universal Fluctuations in Correlated Systems"
N. W. Watkins, S. C. Chapman, G. Rowlands
This is a comment on "Universal Fluctuations in Correlated Systems", by Bramwell et al, Phys. Rev. Lett., 84, 3744 (2000.
Scaling of solar wind epsilon and the AU, AL and AE indices
B. Hnat, S. C. Chapman, G. Rowlands +2
We apply the finite size scaling technique to quantify the statistical properties of fluctuations in AU, AL and AE indices and in the epsilon parameter that represents energy input…
Characterising anomalous transport in accretion disks from X-ray observations
J. Greenhough, S. C. Chapman, S. Chaty +2
Whilst direct observations of internal transport in accretion disks are not yet possible, measurement of the energy emitted from accreting astrophysical systems can provide useful…
Extremum statistics: A framework for data analysis
Sandra Chapman, George Rowlands, Nicholas Watkins
Recent work has suggested that in highly correlated systems, such as sandpiles, turbulent fluids, ignited trees in forest fires and magnetization in a ferromagnet close to a critic…
Testing the SOC hypothesis for the magnetosphere
N. W. Watkins, M. P. Freeman, S. C. Chapman +1
As noted by Chang, the hypothesis of Self-Organised Criticality provides a theoretical framework in which the low dimensionality seen in magnetospheric indices can be combined with…