Generation of large-scale magnetic fields by small-scale dynamo in shear flows
Abstract
We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the "shear-current" effect. Furthermore, given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic nature of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.
- Authors:
-
- Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Max Planck & Princeton Ctr Plasma Phys, Princeton, NJ 08543 USA; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States)
- Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences; Max Planck & Princeton Ctr Plasma Phys, Princeton, NJ 08543 USA; Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1259593
- Alternate Identifier(s):
- OSTI ID: 1224124
- Report Number(s):
- PPPL-5148
Journal ID: ISSN 0031-9007; PRLTAO
- Grant/Contract Number:
- AC02-09CH11466; AC02-09-CH11466
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physical Review Letters
- Additional Journal Information:
- Journal Volume: 115; Journal Issue: 17; Journal ID: ISSN 0031-9007
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Squire, J., and Bhattacharjee, A. Generation of large-scale magnetic fields by small-scale dynamo in shear flows. United States: N. p., 2015.
Web. doi:10.1103/PhysRevLett.115.175003.
Squire, J., & Bhattacharjee, A. Generation of large-scale magnetic fields by small-scale dynamo in shear flows. United States. https://doi.org/10.1103/PhysRevLett.115.175003
Squire, J., and Bhattacharjee, A. Tue .
"Generation of large-scale magnetic fields by small-scale dynamo in shear flows". United States. https://doi.org/10.1103/PhysRevLett.115.175003. https://www.osti.gov/servlets/purl/1259593.
@article{osti_1259593,
title = {Generation of large-scale magnetic fields by small-scale dynamo in shear flows},
author = {Squire, J. and Bhattacharjee, A.},
abstractNote = {We propose a new mechanism for a turbulent mean-field dynamo in which the magnetic fluctuations resulting from a small-scale dynamo drive the generation of large-scale magnetic fields. This is in stark contrast to the common idea that small-scale magnetic fields should be harmful to large-scale dynamo action. These dynamos occur in the presence of a large-scale velocity shear and do not require net helicity, resulting from off-diagonal components of the turbulent resistivity tensor as the magnetic analogue of the "shear-current" effect. Furthermore, given the inevitable existence of nonhelical small-scale magnetic fields in turbulent plasmas, as well as the generic nature of velocity shear, the suggested mechanism may help explain the generation of large-scale magnetic fields across a wide range of astrophysical objects.},
doi = {10.1103/PhysRevLett.115.175003},
journal = {Physical Review Letters},
number = 17,
volume = 115,
place = {United States},
year = {Tue Oct 20 00:00:00 EDT 2015},
month = {Tue Oct 20 00:00:00 EDT 2015}
}
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