Conversion Layer Controls the Evolution of Magnetic Deflections Near the Alfven Surface
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866917233262854144 |
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| author | Payne, Dominic Akhavan-Tafti, Mojtaba Goodwill, Joshua Badman, Samuel Bandyopadhyay, Riddhi Adhikari, Subash Matthaeus, William Zank, Gary Shi, Chen Stevens, Michael Livi, Roberto Rivera, Yeimy Paulson, Kristoff |
| author_facet | Payne, Dominic Akhavan-Tafti, Mojtaba Goodwill, Joshua Badman, Samuel Bandyopadhyay, Riddhi Adhikari, Subash Matthaeus, William Zank, Gary Shi, Chen Stevens, Michael Livi, Roberto Rivera, Yeimy Paulson, Kristoff |
| contents | We examine the statistics of Alfvenic deflections in both sub-Alfvenic and super-Alfvenic solar wind with particular focus on a common parameter that underlies the definition of switchbacks: the magnetic deflection angle. Our findings are in general agreement with earlier studies that suggest magnetic deflection angles > 90 degrees are very unlikely to occur in sub-Alfvenic regimes. We find that their upper limit exhibits an identifiable trend with the Alfven Mach number Ma, suggesting that gradual steepening of Alfvenic deflections with increasing Ma is a plausible mechanism controlling deflection angles in the young solar wind. Further analysis reveals that large velocity fluctuations tend to be important in the largest sub-Alfvenic magnetic deflections with increasing contributions from the parallel component very close to Ma = 1, while virtually no magnetic deflections in the super-Alfvenic regime exhibit such large velocity perturbations. We also determine the local ratio of radial Poynting flux SR to kinetic energy flux KR and find that large sub-Alfvenic deflection angles tend to be dominated by SR, while super-Alfvenic deflections are eventually dominated by the KR associated with the radial solar wind flow. Our results show that within the vicinity of the Alfven surface (where Ma = 1), there is a critical region of parameter space within which velocity deflections approach the Alfven velocity and KR/SR is close to unity. We refer to this region (where | log10(Ma)| < 0.2) as the conversion layer. The conversion layer may play a significant role in the evolution of magnetic defections by providing the medium for converting magnetic energy to particle energy and likely driving the formation of magnetic switchbacks in super-Alfvenic solar wind. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_22321 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Conversion Layer Controls the Evolution of Magnetic Deflections Near the Alfven Surface Payne, Dominic Akhavan-Tafti, Mojtaba Goodwill, Joshua Badman, Samuel Bandyopadhyay, Riddhi Adhikari, Subash Matthaeus, William Zank, Gary Shi, Chen Stevens, Michael Livi, Roberto Rivera, Yeimy Paulson, Kristoff Solar and Stellar Astrophysics Space Physics We examine the statistics of Alfvenic deflections in both sub-Alfvenic and super-Alfvenic solar wind with particular focus on a common parameter that underlies the definition of switchbacks: the magnetic deflection angle. Our findings are in general agreement with earlier studies that suggest magnetic deflection angles > 90 degrees are very unlikely to occur in sub-Alfvenic regimes. We find that their upper limit exhibits an identifiable trend with the Alfven Mach number Ma, suggesting that gradual steepening of Alfvenic deflections with increasing Ma is a plausible mechanism controlling deflection angles in the young solar wind. Further analysis reveals that large velocity fluctuations tend to be important in the largest sub-Alfvenic magnetic deflections with increasing contributions from the parallel component very close to Ma = 1, while virtually no magnetic deflections in the super-Alfvenic regime exhibit such large velocity perturbations. We also determine the local ratio of radial Poynting flux SR to kinetic energy flux KR and find that large sub-Alfvenic deflection angles tend to be dominated by SR, while super-Alfvenic deflections are eventually dominated by the KR associated with the radial solar wind flow. Our results show that within the vicinity of the Alfven surface (where Ma = 1), there is a critical region of parameter space within which velocity deflections approach the Alfven velocity and KR/SR is close to unity. We refer to this region (where | log10(Ma)| < 0.2) as the conversion layer. The conversion layer may play a significant role in the evolution of magnetic defections by providing the medium for converting magnetic energy to particle energy and likely driving the formation of magnetic switchbacks in super-Alfvenic solar wind. |
| title | Conversion Layer Controls the Evolution of Magnetic Deflections Near the Alfven Surface |
| topic | Solar and Stellar Astrophysics Space Physics |
| url | https://arxiv.org/abs/2601.22321 |