Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence
Minor ions in the solar corona are heated to extreme temperatures, far in excess of those of the electrons and protons that comprise the bulk of the plasma. These highly nonthermal distributions make minor ions sensitive probes of the collisionless processes that heat the corona and power the solar...
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad95fc |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1832589779701596160 |
|---|---|
| author | Michael F. Zhang Matthew W. Kunz Jonathan Squire Kristopher G. Klein |
| author_facet | Michael F. Zhang Matthew W. Kunz Jonathan Squire Kristopher G. Klein |
| author_sort | Michael F. Zhang |
| collection | DOAJ |
| description | Minor ions in the solar corona are heated to extreme temperatures, far in excess of those of the electrons and protons that comprise the bulk of the plasma. These highly nonthermal distributions make minor ions sensitive probes of the collisionless processes that heat the corona and power the solar wind. The recent discovery of the “helicity barrier” offers a mechanism in which imbalanced Alfvénic turbulence in low- β plasmas preferentially heats protons over electrons, generating high-frequency, proton-cyclotron-resonant fluctuations. We use the hybrid-kinetic particle-in-cell code Pegasus++ to drive imbalanced Alfvénic turbulence in a 3D low- β plasma with additional passive ion species, He ^2+ and O ^5+ . A helicity barrier naturally develops, followed by clear phase-space signatures of oblique proton-cyclotron-wave heating and Landau-resonant heating from the imbalanced Alfvénic fluctuations. The former results in characteristically arced ion velocity distribution functions, whose non-bi-Maxwellian features are shown by linear ALPS calculations to be critical to the heating process. Additional features include a steep transition-range electromagnetic spectrum, proton-cyclotron waves propagating in the direction of the imbalance, significantly enhanced proton-to-electron heating ratios, ion temperatures that are considerably more perpendicular with respect to magnetic field, and extreme heating of heavier species in a manner consistent with mass scalings inferred from spacecraft measurements. None of these features are realized in an otherwise equivalent simulation of balanced turbulence. If seen simultaneously in the fast solar wind, these signatures of the helicity barrier would testify to the necessity of incorporating turbulence imbalance in a complete theory for the evolution of the solar wind. |
| format | Article |
| id | doaj-art-9605940f747e44e8b93d2e8b9e211c07 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-9605940f747e44e8b93d2e8b9e211c072025-01-24T08:14:36ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01979212110.3847/1538-4357/ad95fcExtreme Heating of Minor Ions in Imbalanced Solar-wind TurbulenceMichael F. Zhang0https://orcid.org/0000-0002-3987-5977Matthew W. Kunz1https://orcid.org/0000-0003-1676-6126Jonathan Squire2https://orcid.org/0000-0001-8479-962XKristopher G. Klein3https://orcid.org/0000-0001-6038-1923Department of Astrophysical Sciences, Princeton University , Peyton Hall, Princeton, NJ 08544, USA; Princeton Plasma Physics Laboratory , PO Box 451, Princeton, NJ 08543, USADepartment of Astrophysical Sciences, Princeton University , Peyton Hall, Princeton, NJ 08544, USA; Princeton Plasma Physics Laboratory , PO Box 451, Princeton, NJ 08543, USAPhysics Department, University of Otago , 730 Cumberland Street, Dunedin 9016, New ZealandLunar and Planetary Laboratory, University of Arizona , Tucson, AZ 85721, USAMinor ions in the solar corona are heated to extreme temperatures, far in excess of those of the electrons and protons that comprise the bulk of the plasma. These highly nonthermal distributions make minor ions sensitive probes of the collisionless processes that heat the corona and power the solar wind. The recent discovery of the “helicity barrier” offers a mechanism in which imbalanced Alfvénic turbulence in low- β plasmas preferentially heats protons over electrons, generating high-frequency, proton-cyclotron-resonant fluctuations. We use the hybrid-kinetic particle-in-cell code Pegasus++ to drive imbalanced Alfvénic turbulence in a 3D low- β plasma with additional passive ion species, He ^2+ and O ^5+ . A helicity barrier naturally develops, followed by clear phase-space signatures of oblique proton-cyclotron-wave heating and Landau-resonant heating from the imbalanced Alfvénic fluctuations. The former results in characteristically arced ion velocity distribution functions, whose non-bi-Maxwellian features are shown by linear ALPS calculations to be critical to the heating process. Additional features include a steep transition-range electromagnetic spectrum, proton-cyclotron waves propagating in the direction of the imbalance, significantly enhanced proton-to-electron heating ratios, ion temperatures that are considerably more perpendicular with respect to magnetic field, and extreme heating of heavier species in a manner consistent with mass scalings inferred from spacecraft measurements. None of these features are realized in an otherwise equivalent simulation of balanced turbulence. If seen simultaneously in the fast solar wind, these signatures of the helicity barrier would testify to the necessity of incorporating turbulence imbalance in a complete theory for the evolution of the solar wind.https://doi.org/10.3847/1538-4357/ad95fcSolar windSolar coronal heatingSpace plasmasInterplanetary turbulencePlasma astrophysics |
| spellingShingle | Michael F. Zhang Matthew W. Kunz Jonathan Squire Kristopher G. Klein Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence The Astrophysical Journal Solar wind Solar coronal heating Space plasmas Interplanetary turbulence Plasma astrophysics |
| title | Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence |
| title_full | Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence |
| title_fullStr | Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence |
| title_full_unstemmed | Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence |
| title_short | Extreme Heating of Minor Ions in Imbalanced Solar-wind Turbulence |
| title_sort | extreme heating of minor ions in imbalanced solar wind turbulence |
| topic | Solar wind Solar coronal heating Space plasmas Interplanetary turbulence Plasma astrophysics |
| url | https://doi.org/10.3847/1538-4357/ad95fc |
| work_keys_str_mv | AT michaelfzhang extremeheatingofminorionsinimbalancedsolarwindturbulence AT matthewwkunz extremeheatingofminorionsinimbalancedsolarwindturbulence AT jonathansquire extremeheatingofminorionsinimbalancedsolarwindturbulence AT kristophergklein extremeheatingofminorionsinimbalancedsolarwindturbulence |