A coherent liquid-sodium dynamo to understand the magnetohydrodynamic amplification of magnetic fields

ORAL

Abstract

Accretion disks of plasma create currents responsible for the huge magnetic fields of active galactic nuclei. Circulating iron creates Earth's magnetic field. The question of how small ``seed'' magnetic fields in conducting fluids/plasmas are amplified by factors of tens to millions is called the ``dynamo problem.'' We have simulated the differential rotation of accretion disks with a ``plasma'' consisting of 125 liters of liquid sodium metal constrained between co-rotating cylinders which produce Taylor-Couette flow at Reynolds numbers up to $10^7$. Given a radial seed field of 10 G, our apparatus converted mechanical to magnetic energy to produce an 80-G toroidal field. This effect (called the $\omega$-effect) is predicted in dynamo theory, but our experiment showed, in 2011, the largest gain obtained by any experiment in the world. We attribute this success to the largely coherent flow field in the instrument. We are now studying the $\beta$-effect, in which fluid turbulence dissipates magnetic energy by increasing the effective resistivity of the fluid. The $\beta$-effect is studied by applying an external B-field pulse and observing its penetration into the liquid sodium flows vs time for varying rates of rotation and levels of turbulence.

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Authors

  • Richard Sonnenfeld

    New Mexico Tech Physics Dept., New Mexico Institute of Mining and Technology

  • John Colton

    Brigham Young University Dept. of Physics and Astronomy, Brigham Young University, None, The College of William and Mary/Jefferson Lab, Brigham Young University-Idaho, Blue Ridge Research and Consulting LLC, Air Force Research Laboratory - Wright Patterson Air Force Base, Brigham Young Univ - Provo, Blue Ridge Research and Consulting, University of Utah, SRI International, Utah State University, Utah Valley University, Los Alamos National Laboratory, Professor, Graduate, United States Air Force Academy, Arizona State Univ, SiO2 NanoTech, Entrepix Inc, AFRL, Advisor, Brigham Young University- Provo, University of New Mexico, Univ of Utah, University of Wisconsin -- Madison, New Mexico Tech Physics Dept., Retired, Department of Physics and Astronomy, University of Utah, Department of Physics \& Astronomy, University of Hawai'i, JILA and University of Colorado, Boulder, National Institute of Standards and Technology, Boulder, University of Colorado, Boulder, Lawrence Berkeley National Laboratory, National Institute of Standards and Technology, Space Dynamics Lab, New Mexico Tech, BYU Professor, Brigham Young University -- Provo, Northern Arizona University, University of Colorado Boulder, Colorado State University, University of Utah, Department of Physics, New Mexico State University

  • John Colton

    Brigham Young University Dept. of Physics and Astronomy, Brigham Young University, None, The College of William and Mary/Jefferson Lab, Brigham Young University-Idaho, Blue Ridge Research and Consulting LLC, Air Force Research Laboratory - Wright Patterson Air Force Base, Brigham Young Univ - Provo, Blue Ridge Research and Consulting, University of Utah, SRI International, Utah State University, Utah Valley University, Los Alamos National Laboratory, Professor, Graduate, United States Air Force Academy, Arizona State Univ, SiO2 NanoTech, Entrepix Inc, AFRL, Advisor, Brigham Young University- Provo, University of New Mexico, Univ of Utah, University of Wisconsin -- Madison, New Mexico Tech Physics Dept., Retired, Department of Physics and Astronomy, University of Utah, Department of Physics \& Astronomy, University of Hawai'i, JILA and University of Colorado, Boulder, National Institute of Standards and Technology, Boulder, University of Colorado, Boulder, Lawrence Berkeley National Laboratory, National Institute of Standards and Technology, Space Dynamics Lab, New Mexico Tech, BYU Professor, Brigham Young University -- Provo, Northern Arizona University, University of Colorado Boulder, Colorado State University, University of Utah, Department of Physics, New Mexico State University

  • John Colton

    Brigham Young University Dept. of Physics and Astronomy, Brigham Young University, None, The College of William and Mary/Jefferson Lab, Brigham Young University-Idaho, Blue Ridge Research and Consulting LLC, Air Force Research Laboratory - Wright Patterson Air Force Base, Brigham Young Univ - Provo, Blue Ridge Research and Consulting, University of Utah, SRI International, Utah State University, Utah Valley University, Los Alamos National Laboratory, Professor, Graduate, United States Air Force Academy, Arizona State Univ, SiO2 NanoTech, Entrepix Inc, AFRL, Advisor, Brigham Young University- Provo, University of New Mexico, Univ of Utah, University of Wisconsin -- Madison, New Mexico Tech Physics Dept., Retired, Department of Physics and Astronomy, University of Utah, Department of Physics \& Astronomy, University of Hawai'i, JILA and University of Colorado, Boulder, National Institute of Standards and Technology, Boulder, University of Colorado, Boulder, Lawrence Berkeley National Laboratory, National Institute of Standards and Technology, Space Dynamics Lab, New Mexico Tech, BYU Professor, Brigham Young University -- Provo, Northern Arizona University, University of Colorado Boulder, Colorado State University, University of Utah, Department of Physics, New Mexico State University

  • John Colton

    Brigham Young University Dept. of Physics and Astronomy, Brigham Young University, None, The College of William and Mary/Jefferson Lab, Brigham Young University-Idaho, Blue Ridge Research and Consulting LLC, Air Force Research Laboratory - Wright Patterson Air Force Base, Brigham Young Univ - Provo, Blue Ridge Research and Consulting, University of Utah, SRI International, Utah State University, Utah Valley University, Los Alamos National Laboratory, Professor, Graduate, United States Air Force Academy, Arizona State Univ, SiO2 NanoTech, Entrepix Inc, AFRL, Advisor, Brigham Young University- Provo, University of New Mexico, Univ of Utah, University of Wisconsin -- Madison, New Mexico Tech Physics Dept., Retired, Department of Physics and Astronomy, University of Utah, Department of Physics \& Astronomy, University of Hawai'i, JILA and University of Colorado, Boulder, National Institute of Standards and Technology, Boulder, University of Colorado, Boulder, Lawrence Berkeley National Laboratory, National Institute of Standards and Technology, Space Dynamics Lab, New Mexico Tech, BYU Professor, Brigham Young University -- Provo, Northern Arizona University, University of Colorado Boulder, Colorado State University, University of Utah, Department of Physics, New Mexico State University

  • John Colton

    Brigham Young University Dept. of Physics and Astronomy, Brigham Young University, None, The College of William and Mary/Jefferson Lab, Brigham Young University-Idaho, Blue Ridge Research and Consulting LLC, Air Force Research Laboratory - Wright Patterson Air Force Base, Brigham Young Univ - Provo, Blue Ridge Research and Consulting, University of Utah, SRI International, Utah State University, Utah Valley University, Los Alamos National Laboratory, Professor, Graduate, United States Air Force Academy, Arizona State Univ, SiO2 NanoTech, Entrepix Inc, AFRL, Advisor, Brigham Young University- Provo, University of New Mexico, Univ of Utah, University of Wisconsin -- Madison, New Mexico Tech Physics Dept., Retired, Department of Physics and Astronomy, University of Utah, Department of Physics \& Astronomy, University of Hawai'i, JILA and University of Colorado, Boulder, National Institute of Standards and Technology, Boulder, University of Colorado, Boulder, Lawrence Berkeley National Laboratory, National Institute of Standards and Technology, Space Dynamics Lab, New Mexico Tech, BYU Professor, Brigham Young University -- Provo, Northern Arizona University, University of Colorado Boulder, Colorado State University, University of Utah, Department of Physics, New Mexico State University