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A radially decreasing toroidal rotation frequency can have a stabilizing effect on nonaxisymmetric magnetohydrodynamic (MHD) instabilities. We show that this is a consequence of the Coriolis effect that induces a restoring pressure gradient force when plasma is perturbed radially. In a rotating cylindrical plasma, this Coriolis-pressure effect is canceled by the centrifugal effect responsible for the magnetorotational instability. In a magnetically confined toroidal plasma, a large aspect ratio expansion shows that only half of the effect is canceled. This analytical result is confirmed by numerical computations. When the plasma rotates faster toroidally in the core than near the edge, the effect can contribute to the formation of transport barriers by stabilizing MHD instabilities. [ABSTRACT FROM AUTHOR]

Nonlinear electromagnetic stabilization by suprathermal pressure gradients found in specific regimes is shown to be a key factor in reducing tokamak microturbulence, augmenting significantly the thermal pressure electromagnetic stabilization. Based on nonlinear gyrokinetic simulations investigating a set of ion heat transport experiments on the JET tokamak, described by Mantica et al. [Phys. Rev. Lett. 107, 135004 (2011)], this result explains the experimentally observed ion heat flux and stiffness reduction. These findings are expected to improve the extrapolation of advanced tokamak scenarios to reactor relevant regimes. [ABSTRACT FROM AUTHOR]

The manipulation of magnetic particles in a continuous flow with magnetic fields is central to several biomedical applications, including magnetic cell separation and magnetic drug targeting. A simplified two-dimensional (2D) equation describing the motion of particles in a planar Poiseuille flow is considered for various magnetic field configurations. Exact analytical solutions are derived for the particle motion under the influence of a constant magnetization force and a force decaying as a power of the source distance, e.g., due to a current carrying wire or a magnetized cylinder. For a source distance much larger than the transversal size of the flow, a general solution is derived and applied to the important case of a magnetic dipole. This solution is used to investigate the dependence of the particle capture efficiency on the dipole orientation. A correction factor to convert the obtained 2D results to a three-dimensional cylindrical geometry is derived and validated against computational simulations. Simulations are also used to investigate parameter ranges beyond the region of applicability of the analytical results and to investigate more complex magnetic field configurations.