Magnetized Turbulent Dynamo in Protogalaxies

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The prevailing theory for the origin of cosmic magnetic fields is that they have been amplified to their present values by the turbulent dynamo inductive action in the protogalactic and galactic medium. Up to now, in calculation of the turbulent dynamo, it has been customary to assume that there is no back reaction of the magnetic field on the turbulence, as long as the magnetic energy is less than the turbulent kinetic energy. This assumption leads to the kinematic dynamo theory. However, the applicability of this theory to protogalaxies is rather limited. The reason is that in protogalaxies the temperature ... continued below

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493 Kilobytes pages

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Malyshkin, Leonid & Kulsrud, Russell M. January 28, 2002.

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The prevailing theory for the origin of cosmic magnetic fields is that they have been amplified to their present values by the turbulent dynamo inductive action in the protogalactic and galactic medium. Up to now, in calculation of the turbulent dynamo, it has been customary to assume that there is no back reaction of the magnetic field on the turbulence, as long as the magnetic energy is less than the turbulent kinetic energy. This assumption leads to the kinematic dynamo theory. However, the applicability of this theory to protogalaxies is rather limited. The reason is that in protogalaxies the temperature is very high, and the viscosity is dominated by magnetized ions. As the magnetic field strength grows in time, the ion cyclotron time becomes shorter than the ion collision time, and the plasma becomes strongly magnetized. As a result, the ion viscosity becomes the Braginskii viscosity. Thus, in protogalaxies the back reaction sets in much earlier, at field strengths much lower than those which correspond to field-turbulence energy equipartition, and the turbulent dynamo becomes what we call the magnetized turbulent dynamo. In this paper we lay the theoretical groundwork for the magnetized turbulent dynamo. In particular, we predict that the magnetic energy growth rate in the magnetized dynamo theory is up to ten times larger than that in the kinematic dynamo theory. We also briefly discuss how the Braginskii viscosity can aid the development of the inverse cascade of magnetic energy after the energy equipartition is reached.

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493 Kilobytes pages

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INIS; OSTI as DE00796126

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  • Other Information: PBD: 28 Jan 2002

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  • Report No.: PPPL-3672.pdf
  • Grant Number: AC02-76CH03073
  • DOI: 10.2172/796126 | External Link
  • Office of Scientific & Technical Information Report Number: 796126
  • Archival Resource Key: ark:/67531/metadc741041

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  • January 28, 2002

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  • Oct. 19, 2015, 7:39 p.m.

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  • April 18, 2016, 1 p.m.

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Malyshkin, Leonid & Kulsrud, Russell M. Magnetized Turbulent Dynamo in Protogalaxies, report, January 28, 2002; Princeton, New Jersey. (digital.library.unt.edu/ark:/67531/metadc741041/: accessed October 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.