Helical magnetorotational instability in magnetized Taylor-Couette flow

Wei Liu, Jeremy Goodman, Isom Herron, Hantao Ji

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Hollerbach and Rüdiger have reported a new type of magnetorotational instability (MRI) in magnetized Taylor-Couette flow in the presence of combined axial and azimuthal magnetic fields. The salient advantage of this "helical" MRI (HMRI) is that marginal instability occurs at arbitrarily low magnetic Reynolds and Lundquist numbers, suggesting that HMRI might be easier to realize than standard MRI (axial field only), and that it might be relevant to cooler astrophysical disks, especially those around protostars, which may be quite resistive. We confirm previous results for marginal stability and calculate HMRI growth rates. We show that in the resistive limit, HMRI is a weakly destabilized inertial oscillation propagating in a unique direction along the axis. But we report other features of HMRI that make it less attractive for experiments and for resistive astrophysical disks. Large axial currents are required. More fundamentally, instability of highly resistive flow is peculiar to infinitely long or periodic cylinders: finite cylinders with insulating endcaps are shown to be stable in this limit, at least if viscosity is neglected. Also, Keplerian rotation profiles are stable in the resistive limit regardless of axial boundary conditions. Nevertheless, the addition of a toroidal field lowers thresholds for instability even in finite cylinders.

Original languageEnglish (US)
Article number056302
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume74
Issue number5
DOIs
StatePublished - 2006
Externally publishedYes

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Taylor-Couette Flow
Couette flow
astrophysics
protostars
coolers
Viscosity
Magnetic Field
Oscillation
Boundary conditions
Calculate
viscosity
boundary conditions
oscillations
thresholds
Experiment
profiles
magnetic fields

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Condensed Matter Physics
  • Statistical and Nonlinear Physics
  • Mathematical Physics

Cite this

Helical magnetorotational instability in magnetized Taylor-Couette flow. / Liu, Wei; Goodman, Jeremy; Herron, Isom; Ji, Hantao.

In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, Vol. 74, No. 5, 056302, 2006.

Research output: Contribution to journalArticle

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