Wave Generation and Energetic Electron Scattering in Solar Flares
We conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T _∥ > T _⊥ temperature anisotropy maintained by continuous injection at the boun...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ace59e |
| _version_ | 1797698120209924096 |
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| author | Hanqing Ma J. F. Drake M. Swisdak |
| author_facet | Hanqing Ma J. F. Drake M. Swisdak |
| author_sort | Hanqing Ma |
| collection | DOAJ |
| description | We conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T _∥ > T _⊥ temperature anisotropy maintained by continuous injection at the boundaries. The anisotropic distribution excites oblique whistler waves and filamentary-like Weibel instabilities. Electron velocity distributions taken after the system has reached a steady state show that these instabilities inhibit the heat flux and drive the total distributions toward isotropy. Electron trajectories in velocity space show a circular-like diffusion along constant energy surfaces in the wave frame. The key parameter controlling the scattering rate is the average speed, or drift speed v _d , of the heat flux compared with the electron Alfvén speed v _Ae , with higher drift speeds producing stronger fluctuations and a more significant reduction of the heat flux. Reducing the density of the electrons carrying the heat flux by 50% does not significantly affect the scattering rate. A scaling law for the electron scattering rate versus v _d / v _Ae is deduced from the simulations. The implications of these results for understanding energetic electron transport during energy release in solar flares are discussed. |
| first_indexed | 2024-03-12T03:49:40Z |
| format | Article |
| id | doaj.art-97e5394259124d5b8e2a236be2d0c30f |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:49:40Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-97e5394259124d5b8e2a236be2d0c30f2023-09-03T12:28:40ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195412110.3847/1538-4357/ace59eWave Generation and Energetic Electron Scattering in Solar FlaresHanqing Ma0https://orcid.org/0000-0002-3422-8519J. F. Drake1https://orcid.org/0000-0002-9150-1841M. Swisdak2https://orcid.org/0000-0002-5435-3544Department of Physics, University of Maryland , College Park, MD 20740, USA ; hanqing@umd.eduDepartment of Physics, University of Maryland , College Park, MD 20740, USA ; hanqing@umd.eduIREAP, University of Maryland , College Park, MD 20742, USAWe conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T _∥ > T _⊥ temperature anisotropy maintained by continuous injection at the boundaries. The anisotropic distribution excites oblique whistler waves and filamentary-like Weibel instabilities. Electron velocity distributions taken after the system has reached a steady state show that these instabilities inhibit the heat flux and drive the total distributions toward isotropy. Electron trajectories in velocity space show a circular-like diffusion along constant energy surfaces in the wave frame. The key parameter controlling the scattering rate is the average speed, or drift speed v _d , of the heat flux compared with the electron Alfvén speed v _Ae , with higher drift speeds producing stronger fluctuations and a more significant reduction of the heat flux. Reducing the density of the electrons carrying the heat flux by 50% does not significantly affect the scattering rate. A scaling law for the electron scattering rate versus v _d / v _Ae is deduced from the simulations. The implications of these results for understanding energetic electron transport during energy release in solar flares are discussed.https://doi.org/10.3847/1538-4357/ace59eActive solar coronaPlasma physicsSolar coronal wavesSolar flares |
| spellingShingle | Hanqing Ma J. F. Drake M. Swisdak Wave Generation and Energetic Electron Scattering in Solar Flares The Astrophysical Journal Active solar corona Plasma physics Solar coronal waves Solar flares |
| title | Wave Generation and Energetic Electron Scattering in Solar Flares |
| title_full | Wave Generation and Energetic Electron Scattering in Solar Flares |
| title_fullStr | Wave Generation and Energetic Electron Scattering in Solar Flares |
| title_full_unstemmed | Wave Generation and Energetic Electron Scattering in Solar Flares |
| title_short | Wave Generation and Energetic Electron Scattering in Solar Flares |
| title_sort | wave generation and energetic electron scattering in solar flares |
| topic | Active solar corona Plasma physics Solar coronal waves Solar flares |
| url | https://doi.org/10.3847/1538-4357/ace59e |
| work_keys_str_mv | AT hanqingma wavegenerationandenergeticelectronscatteringinsolarflares AT jfdrake wavegenerationandenergeticelectronscatteringinsolarflares AT mswisdak wavegenerationandenergeticelectronscatteringinsolarflares |