Direct observations of anomalous resistivity and diffusion in collisionless plasmaShow others and affiliations
2022 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 2954Article in journal (Refereed) Published
Abstract [en]
Coulomb collisions provide plasma resistivity and diffusion but in many low-density astrophysical plasmas such collisions between particles are extremely rare. Scattering of particles by electromagnetic waves can lower the plasma conductivity. Such anomalous resistivity due to wave-particle interactions could be crucial to many processes, including magnetic reconnection. It has been suggested that waves provide both diffusion and resistivity, which can support the reconnection electric field, but this requires direct observation to confirm. Here, we directly quantify anomalous resistivity, viscosity, and cross-field electron diffusion associated with lower hybrid waves using measurements from the four Magnetospheric Multiscale (MMS) spacecraft. We show that anomalous resistivity is approximately balanced by anomalous viscosity, and thus the waves do not contribute to the reconnection electric field. However, the waves do produce an anomalous electron drift and diffusion across the current layer associated with magnetic reconnection. This leads to relaxation of density gradients at timescales of order the ion cyclotron period, and hence modifies the reconnection process. It is suggested that waves can provide both diffusion and resistivity that can potentially support the reconnection electric field in low-density astrophysical plasmas. Here, the authors show, using direct spacecraft measurements, that the waves contribute to anomalous diffusion but do not contribute to the reconnection electric field.
Place, publisher, year, edition, pages
Springer Nature , 2022. Vol. 13, no 1, article id 2954
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-313776DOI: 10.1038/s41467-022-30561-8ISI: 000800650200003PubMedID: 35618713Scopus ID: 2-s2.0-85130716001OAI: oai:DiVA.org:kth-313776DiVA, id: diva2:1739674
Note
QC 20230228
2022-06-102023-02-272023-03-28Bibliographically approved