# Helical magnetorotational instability in a Taylor-Couette flow with strongly reduced Ekman pumping.

@article{Stefani2009HelicalMI, title={Helical magnetorotational instability in a Taylor-Couette flow with strongly reduced Ekman pumping.}, author={Frank Stefani and Gunter Gerbeth and Thomas Gundrum and Rainer Hollerbach and Jānis Priede and G. R{\"u}diger and Jacek Szklarski}, journal={Physical review. E, Statistical, nonlinear, and soft matter physics}, year={2009}, volume={80 6 Pt 2}, pages={ 066303 } }

The magnetorotational instability (MRI) is thought to play a key role in the formation of stars and black holes by sustaining the turbulence in hydrodynamically stable Keplerian accretion disks. In previous experiments the MRI was observed in a liquid metal Taylor-Couette flow at moderate Reynolds numbers by applying a helical magnetic field. The observation of this helical MRI (HMRI) was interfered with a significant Ekman pumping driven by solid end caps that confined the instability only to… Expand

#### Figures and Topics from this paper

#### 76 Citations

Transition to magnetorotational turbulence in Taylor–Couette flow with imposed azimuthal magnetic field

- Physics
- 2015

The magnetorotational instability (MRI) is thought to be a powerful source of turbulence and momentum transport in astrophysical accretion discs, but obtaining observational evidence of its operation… Expand

Quasi-two-dimensional nonlinear evolution of helical magnetorotational instability in a magnetized Taylor-Couette flow

- Physics
- 2017

Magnetorotational instability (MRI) is one of the fundamental processes in astrophysics, driving angular momentum transport and mass accretion in a wide variety of cosmic objects. Despite much… Expand

Dynamics and transport of instabilities in magnetized quasi-Keplerian Taylor-Couette flows

- Physics
- 2018

The stability and transition to turbulence in canonical shear flows have since long been an outstanding scientific problem. One of the most exciting examples of shear flow is Keplerian motion of gas… Expand

The weakly nonlinear magnetorotational instability in a global, cylindrical Taylor-Couette flow

- Physics
- 2016

We conduct a global, weakly nonlinear analysis of the magnetorotational instability (MRI) in a Taylor-Couette flow. This is a multiscale perturbative treatment of the nonideal, axisymmetric MRI near… Expand

The role of boundaries in the magnetorotational instability

- Physics
- 2012

In this paper, we investigate numerically the flow of an electrically conducting fluid in a cylindrical Taylor-Couette flow when an axial magnetic field is applied. To minimize Ekman recirculation… Expand

Local instabilities in magnetized rotational flows: a short-wavelength approach

- Physics, Mathematics
- Journal of Fluid Mechanics
- 2014

Abstract We perform a local stability analysis of rotational flows in the presence of a constant vertical magnetic field and an azimuthal magnetic field with a general radial dependence. Employing… Expand

Liquid metal experiments on the helical magnetorotational instability

- Physics
- 2008

The magnetorotational instability (MRI) plays an essential role in the formation of stars and black holes. By destabilizing hydrodynamically stable Keplerian flows, the MRI triggers turbulence and… Expand

On the relation of standard and helical magnetorotational instability

- Physics, Mathematics
- 2010

The magnetorotational instability (MRI) plays a crucial role for cosmic structure formation by enabling turbulence in Keplerian disks which would be otherwise hydrodynamically stable. With particular… Expand

Stability and instability of hydromagnetic Taylor-Couette flows

- Physics
- 2017

Decades ago S. Lundquist, S. Chandrasekhar, P.H. Roberts and R. J.~Tayler first posed questions about the stability of Taylor-Couette flows of conducting material under the influence of large-scale… Expand

A Unifying Picture of Helical and Azimuthal Magnetorotational Instability, and the Universal Significance of the Liu Limit

- Physics, Mathematics
- 2012

The magnetorotational instability (MRI) plays a key role for cosmic structure formation by triggering turbulence in the rotating flows of accretion disks that would be otherwise hydrodynamically… Expand

#### References

SHOWING 1-10 OF 110 REFERENCES

Absolute versus convective helical magnetorotational instability in a Taylor-Couette flow.

- Physics, Medicine
- Physical review. E, Statistical, nonlinear, and soft matter physics
- 2009

A detailed conventional linear stability analysis with respect to perturbations in the form of Fourier modes that corresponds to the convective instability which is not in general self-sustained is carried out. Expand

Helical magnetorotational instability in magnetized Taylor-Couette flow.

- Physics, Medicine
- Physical review. E, Statistical, nonlinear, and soft matter physics
- 2006

It is shown that in the resistive limit, HMRI is a weakly destabilized inertial oscillation propagating in a unique direction along the axis, and features of HMRI that make it less attractive for experiments and for resistive astrophysical disks are reported. Expand

Inductionless magnetorotational instability in a Taylor-Couette flow with a helical magnetic field.

- Physics
- 2007

We consider the magnetorotational instability (MRI) of a hydrodynamically stable Taylor-Couette flow with a helical external magnetic field in the inductionless approximation defined by a zero… Expand

NOISE-SUSTAINED CONVECTIVE INSTABILITY IN A MAGNETIZED TAYLOR-COUETTE FLOW

- Physics
- 2009

The helical magnetorotational instability of the magnetized Taylor-Couette flow is studied numerically in a finite cylinder. A distant upstream insulating boundary is shown to stabilize the… Expand

Ekman-Hartmann layer in a magnetohydrodynamic Taylor-Couette flow.

- Physics, Medicine
- Physical review. E, Statistical, nonlinear, and soft matter physics
- 2007

It is shown that the end plates introduce, besides the well-known Ekman circulation, similar magnetic effects which arise for infinite, rotating plates, horizontally unbounded by any walls, and that the currents induced by the plates can give rise to instability for the considered parameters. Expand

Experimental evidence for magnetorotational instability in a Taylor-Couette flow under the influence of a helical magnetic field.

- Physics, Medicine
- Physical review letters
- 2006

Results of a Taylor-Couette experiment with the liquid metal alloy GaInSn are presented, showing evidence for the existence of the magnetorotational instability at Reynolds numbers of order 1000 and HartmannNumbers of order 10. Expand

Magnetized Ekman layer and Stewartson layer in a magnetized Taylor-Couette flow.

- Physics, Medicine
- Physical review. E, Statistical, nonlinear, and soft matter physics
- 2008

In this paper we present axisymmetric nonlinear simulations of magnetized Ekman and Stewartson layers in a magnetized Taylor-Couette flow with a centrifugally stable angular-momentum profile and with… Expand

Nonlinear simulations of magnetic Taylor‐Couette flow with currentfree helical magnetic fields

- Physics
- 2006

Themagnetorotational instability (MRI) in cylindrical Taylor-Couette flow with external helical magnetic field is simulated for infinite and finite aspect ratios. We solve the MHD equations in their… Expand

Pseudo-magnetorotational instability in a Taylor-Dean flow between electrically connected cylinders.

- Physics, Medicine
- Physical review. E, Statistical, nonlinear, and soft matter physics
- 2009

There is no hydrodynamic stability limit defined in the terms of the critical ratio of rotation rates of inner and outer cylinders that would allow one to distinguish a hydrodynamically instability from the HMRI, and these effects can critically interfere with experimental as well as numerical determination of MRI. Expand

The stability of MHD Taylor‐Couette flow with current‐free spiral magnetic fields between conducting cylinders

- Physics
- 2005

We study the magnetorotational instability in cylindrical Taylor-Couette flow, with the (vertically unbounded) cylinders taken to be perfect conductors, and with externally imposed spiral magnetic… Expand