Gyrokinetic simulations including the centrifugal force in a rotating tokamak plasma

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3491110· OSTI ID:21421246

Casson, F J; Camenen, Y; Hornsby, W A; Snodin, A P; Szepesi, G ^[1]; Peeters, A G ^[2]; Angioni, C ^[3]

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1. Centre for Fusion, Space, and Astrophysics, University of Warwick, CV4 7AL, Coventry (United Kingdom)
2. University of Bayreuth, Universitaetsstrasse 30, Bayreuth 95447 (Germany)
3. Max-Planck-Institut fuer Plasmaphysik, IPP-EURATOM Association, D-85748 Garching bei Muenchen (Germany)

Tokamak experiments operate with a rotating plasma, with toroidal velocity which can be driven externally but can also arise spontaneously. In the frame that corotates with the plasma, the effects of the centrifugal force are felt through a centrifugal drift and an enhanced mirror force [Peeters et al., Phys. Plasmas 16, 042310 (2009)]. These inertial terms become important in the case of strong rotation, as is common in spherical devices, and are also important for heavy impurity ions even at small toroidal velocities. In this work, the first gyrokinetic simulations including the centrifugal force in a strongly rotating plasma are presented. The enhanced mirror force redistributes density over a flux surface and modifies the trapping condition, destabilizing trapped electron modes. At intermediate scales this can result in promotion of the trapped electron mode over the ion temperature gradient (ITG) mode as the dominant instability, which under marginal conditions could result in an enhanced electron heat flux. The centrifugal drift acts to damp the residual zonal flow of the geoacoustic mode, while its frequency is increased. For nonlinear ITG dominated turbulence, increased trapped electron drive and reduced zonal flow lead to an increase in ion heat diffusivity if the increased rotation is not accompanied by rotational shear stabilization. An increased fraction of slow trapped electrons enhances the convective particle pinch, leading to an increase in the steady state density gradient with strong rotation. Linear ITG mode results show an increased pinch of heavy trace impurities due to their strong centrifugal trapping.

• OSTI ID: 21421246
• Journal Information: Physics of Plasmas, Vol. 17, Issue 10; Other Information: DOI: 10.1063/1.3491110; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ION TEMPERATURE
MAGNETIC SURFACES
MAGNETOHYDRODYNAMICS
NONLINEAR PROBLEMS
PLASMA IMPURITIES
PLASMA INSTABILITY
PLASMA SIMULATION
ROTATING PLASMA
TEMPERATURE GRADIENTS
TOKAMAK DEVICES
TRAPPED ELECTRONS
TURBULENCE
CLOSED PLASMA DEVICES
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
FLUID MECHANICS
HYDRODYNAMICS
IMPURITIES
INSTABILITY
LEPTONS
MAGNETIC FIELD CONFIGURATIONS
MECHANICS
PLASMA
SIMULATION
THERMONUCLEAR DEVICES