SC13 Denver, CO

The International Conference for High Performance Computing, Networking, Storage and Analysis

Visualization and Analysis of Coherent Structures, Intermittent Turbulence, and Dissipation in High-Temperature Plasmas.

Authors: Burlen Loring (Lawrence Berkeley National Laboratory), Homa Karimabadi (University of California San Diego), Vadim Rortershteyn (University of California San Diego), Minping Wan (University of Delaware), William Matthaeus (University of Delaware), William Daughton (Los Alamos National Laboratory), Pin Wu (University of Delaware), Michael Shay (University of Delaware), Joe Borovsky (Space Science Institute), Ersilia Leonardis (University of Warwick), Sandra Chapman (University of Warwick), Takuma Nakamura (Los Alamos National Laboratory)

Abstract: An unsolved problem in plasma turbulence is how energy is dissipated at small scales. Particle collisions are too infrequent in hot plasmas to provide the necessary dissipation. Simulations either treat the fluid scales and impose an ad-hoc form of dissipation (e.g.,resistivity) or consider dissipation arising from resonant damping of small amplitude disturbances where damping rates are found to be comparable to that predicted from linear theory.Here, we report kinetic simulations that span the macroscopic fluid scales down to the motion of electrons. We find that turbulent cascade leads to generation of coherent structures in the form of current sheets that steepen to electron scales, triggering strong localized heating of the plasma.The dominant heating mechanism is due to parallel electric fields associated with the current sheets, leading to anisotropic electron and ion distributions. The motion of coherent structures also generates waves that are emitted into the ambient plasma in form of highly oblique compressional and shear Alfven modes. In 3D, modes propagating at other angles can also be generated. This indicates that intermittent plasma turbulence will in general consist of both coherent structures and waves.However, the current sheet heating is found to be locally several orders of magnitude more efficient than wave damping and is sufficient to explain the observed heating rates in the solar wind. In this work the visualization and analysis; new visualization software; and the use of supercomputing visualization resources lead to breakthroughs in the understanding of fundamental physical processes responsible for turbulent heating of the solar wind.

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