Magnetogenesis in a Collisionless Plasma: From Weibel Instability to Turbulent Dynamo
Journal Article
·
· The Astrophysical Journal
- Princeton Univ., NJ (United States); Institute for Advanced Study, Princeton, NJ (United States)
- Flatiron Institute, New York, NY (United States)
- Princeton Univ., NJ (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Univ. of Colorado, Boulder, CO (United States)
We report on a first-principles numerical and theoretical study of plasma dynamo in a fully kinetic framework. By applying an external mechanical force to an initially unmagnetized plasma, we develop a self-consistent treatment of the generation of “seed” magnetic fields, the formation of turbulence, and the inductive amplification of fields by the fluctuation dynamo. Driven large-scale motions in an unmagnetized, weakly collisional plasma are subject to strong phase mixing, which leads to the development of thermal pressure anisotropy. This anisotropy triggers the Weibel instability, which produces filamentary “seed” magnetic fields on plasma-kinetic scales. The plasma is thereby magnetized, enabling efficient stretching and folding of the fields by the plasma motions and the development of Larmor-scale kinetic instabilities such as the firehose and mirror. The scattering of particles off the associated microscale magnetic fluctuations provides an effective viscosity, regulating the field morphology and turbulence. During this process, the seed field is further amplified by the fluctuation dynamo until energy equipartition with the turbulent flow is reached. By demonstrating that equipartition magnetic fields can be generated from an initially unmagnetized plasma through large-scale turbulent flows, this work has important implications for the origin and amplification of magnetic fields in the intracluster and intergalactic mediums.
- Research Organization:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Sponsoring Organization:
- National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); USDOE
- OSTI ID:
- 2310904
- Journal Information:
- The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 960; ISSN 0004-637X
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fluctuation Dynamo in a Collisionless, Weakly Magnetized Plasma
Critical magnetic Reynolds number of the turbulent dynamo in collisionless plasmas
Journal Article
·
Wed Aug 15 20:00:00 EDT 2018
· The Astrophysical Journal. Letters
·
OSTI ID:1466006
Critical magnetic Reynolds number of the turbulent dynamo in collisionless plasmas
Journal Article
·
Thu Dec 21 19:00:00 EST 2023
· Monthly Notices of the Royal Astronomical Society
·
OSTI ID:2341803