EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Dissipation measures in weakly-collisional plasmas

Paul Cassak1, Oreste Pezzi2,3,4, Haoming Liang5, Jimmy Juno6, Christain Vasconez7, Luca Sorriso-Valvo8, Denise Perrone9, Sergio Servidio10, Vadim Roytershteyn11, Jason TenBarge12, and William Matthaeus13
Paul Cassak et al.
  • 1West Virginia University (
  • 2Gran Sasso Science Institut
  • 3INFN/Laboratori Nazionali del Gran Sasso
  • 4Istituto per la Scienza e Tecnologia dei Plasmi
  • 5University of Alabama in Huntsville
  • 6University of Iowa
  • 7Escuela Politécnica Nacional
  • 8Swedish Institute of Space Physics
  • 9ASI – Italian Space Agency
  • 10Università della Calabria
  • 11Space Science Institute
  • 12Princeton University
  • 13University of Delaware

The physical foundations of the dissipation of energy and the associated heating in weakly collisional plasmas are poorly understood. Here, we compare and contrast several measures that have been used to characterize energy dissipation and kinetic-scale conversion in plasmas by means of a suite of kinetic numerical simulations describing both magnetic reconnection and decaying plasma turbulence. We adopt three different numerical codes that can also include inter-particle collisions: the fully-kinetic particle-in-cell vpic, the fully-kinetic continuum Gkeyll, and the Eulerian Hybrid Vlasov-Maxwell (HVM) code. We differentiate between i) four energy-based parameters, whose definition is related to energy transfer in a fluid description of a plasma, and ii) four distribution function-based parameters, requiring knowledge of the particle velocity distribution function. There is overall agreement between the dissipation measures obtained in the PIC and continuum reconnection simulations, with slight differences due to the presence/absence of secondary islands in the two simulations. There are also many qualitative similarities between the signatures in the reconnection simulations and the self-consistent current sheets that form in turbulence, although the latter exhibits significant variations compared to the reconnection results. All the parameters confirm that dissipation occurs close to regions of intense magnetic stresses, thus exhibiting local correlation. The distribution function-based measures show a broader width compared to energy-based proxies, suggesting that energy transfer is co-localized at coherent structures, but can affect the particle distribution function in wider regions. The effect of inter-particle collisions on these parameters is finally discussed.

How to cite: Cassak, P., Pezzi, O., Liang, H., Juno, J., Vasconez, C., Sorriso-Valvo, L., Perrone, D., Servidio, S., Roytershteyn, V., TenBarge, J., and Matthaeus, W.: Dissipation measures in weakly-collisional plasmas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3210,, 2021.


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