Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field
Using particle-in-cell simulations of magnetic reconnection (MR), we investigate how the changing magnetic guide field strength impacts the evolution of electron Kelvin–Helmholtz instability (EKHI) and the associated Fermi electron acceleration proposed by H. Che & G. P. Zank. Through this inves...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/adbc60 |
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| author | C. Crawford H. Che G. P. Zank A. O. Benz |
| author_facet | C. Crawford H. Che G. P. Zank A. O. Benz |
| author_sort | C. Crawford |
| collection | DOAJ |
| description | Using particle-in-cell simulations of magnetic reconnection (MR), we investigate how the changing magnetic guide field strength impacts the evolution of electron Kelvin–Helmholtz instability (EKHI) and the associated Fermi electron acceleration proposed by H. Che & G. P. Zank. Through this investigation, an Alfvénic-like Fermi electron acceleration mechanism is discovered for strong guide field MR B _g / B _0 > 2.5, where B _g is the magnetic guide field. The electrons are accelerated by the intensive electric potential produced through $\delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}}\times {\boldsymbol{B}}$ , where the ion velocity fluctuations $\delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}}$ propagate parallel to the direction of the Alfvén-like waves. Differing from the two-stage second-order Fermi acceleration produced by the stochastic electric field of EKHI, the Alfvén-like wave mechanism is a much more efficient one-stage process that produces a much harder power-law electron energy spectrum, with an index ∼2, than that of the EKHI, with an index ∼4. |
| format | Article |
| id | doaj-art-c28f7c11adda402199c35c848336a85d |
| institution | OA Journals |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj-art-c28f7c11adda402199c35c848336a85d2025-08-20T02:28:07ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01983212010.3847/1538-4357/adbc60Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide FieldC. Crawford0https://orcid.org/0000-0001-5834-0807H. Che1https://orcid.org/0000-0002-2240-6728G. P. Zank2https://orcid.org/0000-0002-4642-6192A. O. Benz3https://orcid.org/0000-0001-9777-9177Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville , Huntsville, AL 35805, USA; Department of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USACenter for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville , Huntsville, AL 35805, USA; Department of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USACenter for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville , Huntsville, AL 35805, USA; Department of Space Science, University of Alabama in Huntsville , Huntsville, AL 35899, USAUniversity of Applied Sciences and Arts Northwestern Switzerland , CH-5210 Windisch, Switzerland; Institute for Particle Physics and Astrophysics , ETH Zürich, 8093, Zürich, SwitzerlandUsing particle-in-cell simulations of magnetic reconnection (MR), we investigate how the changing magnetic guide field strength impacts the evolution of electron Kelvin–Helmholtz instability (EKHI) and the associated Fermi electron acceleration proposed by H. Che & G. P. Zank. Through this investigation, an Alfvénic-like Fermi electron acceleration mechanism is discovered for strong guide field MR B _g / B _0 > 2.5, where B _g is the magnetic guide field. The electrons are accelerated by the intensive electric potential produced through $\delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}}\times {\boldsymbol{B}}$ , where the ion velocity fluctuations $\delta {{\boldsymbol{U}}}_{{\boldsymbol{i}}}$ propagate parallel to the direction of the Alfvén-like waves. Differing from the two-stage second-order Fermi acceleration produced by the stochastic electric field of EKHI, the Alfvén-like wave mechanism is a much more efficient one-stage process that produces a much harder power-law electron energy spectrum, with an index ∼2, than that of the EKHI, with an index ∼4.https://doi.org/10.3847/1538-4357/adbc60Solar magnetic reconnectionSolar flaresSolar energetic particles |
| spellingShingle | C. Crawford H. Che G. P. Zank A. O. Benz Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field The Astrophysical Journal Solar magnetic reconnection Solar flares Solar energetic particles |
| title | Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field |
| title_full | Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field |
| title_fullStr | Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field |
| title_full_unstemmed | Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field |
| title_short | Transition from Vortical to Alfvénic-like Fermi Electron Acceleration in Magnetic Reconnection with Increasing Guide Field |
| title_sort | transition from vortical to alfvenic like fermi electron acceleration in magnetic reconnection with increasing guide field |
| topic | Solar magnetic reconnection Solar flares Solar energetic particles |
| url | https://doi.org/10.3847/1538-4357/adbc60 |
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