Alfvén waves and rotation of collisional plasmas in tokamaks

Tsypin, V. S.; Elfimov, A. G.; Azevedo, C. A. de; Assis, A. S. de

doi:10.1063/1.871716

Cited by 17 publications

(17 citation statements)

References 12 publications

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“…For instability, the real part of either of the roots s Ϯ has to be positive. From the point of view of the ponderomotive force, which is our present interest, the first case is the one that has been considered in previous works, [8][9][10][11][12] represented by the direct momentum transfer of toroidal and poloidal PM forces contained in A 4 . The spin-up, given by the exponentials, may arise from a radial flow produced by the PM force, if it is large enough to overcome the damping due to collisions and viscosity.…”

Section: ͑5͒mentioning

confidence: 99%

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Induction of poloidal rotation by a radial ponderomotive force of electron cyclotron waves

Martinell

Gutiérrez-Tapia

2001

Physics of Plasmas

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The nonlinear ponderomotive (PM) force due to high-power rf waves is studied as a drive for plasma rotation. It is shown that poloidal rotation may be driven by a radial PM force, in addition to the usual mechanism of direct angular momentum transfer from a poloidal PM force. Here, the effect of a radial PM force producing a radial plasma flow in the presence of viscous damping and neutral collisions is considered. The PM force is produced around an electron cyclotron resonant surface at a specific poloidal location, which naturally creates a poloidally asymmetric steady radial flow, when friction is present. The flow can also arise as a result of poloidal or toroidal PM force components, even in the absence of friction. In toroidal geometry this situation is unstable due to the Stringer spin-up mechanism, for a high enough power of the rf waves. This process is most important near the outer regions of the plasma, where it can then give rise to a high confinement mode (H mode), once a sheared poloidal flow is established. The advantage of this method of driving rotation is that the wave can propagate radially and when it is absorbed at the resonant surface the radial PM force is produced, instead of launching a wave in the poloidal direction. It is shown that this effect may be large enough for electron-cyclotron resonance heating, due to the small width of the resonant surface.

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Section: ͑5͒mentioning

confidence: 99%

“…8 According to these works only the angular components of the PM force can produce rotation. 11,12 We show here that a radial PM force that is poloidally asymmetric can drive poloidal rotation, in the presence of particle collisions. It is based on the Stringer spin-up mechanism.…”

Section: Introductionmentioning

confidence: 97%

Induction of poloidal rotation by a radial ponderomotive force of electron cyclotron waves

Martinell

Gutiérrez-Tapia

2001

Physics of Plasmas

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“…In the case of KAW, the poloidal forces 18,19 affecting ions can also be expressed via the absorbed power 2,3…”

Section: Differential Equations For Ion Viscositiesmentioning

confidence: 99%

Anomalous and neoclassical transport suppression by the radial electric field, induced by Alfvén waves in tokamaks

et al. 1999

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The suppression of anomalous transport and/or reduction of neoclassical transport caused by the Alfvén-wave-induced shear of the radial electric field in tokamaks is investigated. The simple quantitative estimates reported in previous papers are checked by a consistent evaluation of the profile of the radial electric field created by the resonant absorption of Alfvén waves. The radial variations of the ion viscosity and heat conductivity across the mode conversion layer are evaluated both in the banana and potato regions. In agreement with previous analytical results, it is shown that the kinetic Alfvén waves may play the role of a convenient mechanism for reduction of anomalous and neoclassical transport and formation of transport barriers in tokamaks.

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“…13 Second, the radial electric field obtained by balancing the ponderomotive force with viscous force has a very large gradient 14 and changes sign across the resonant layer. 15 use this field to induce shear suppression of turbulent convective cells 16,17 and to squeeze trapped particle orbits. 18,19 These promising applications make it worthwhile to carry on the investigation of the interaction of Alfvén waves with thermonuclear plasmas.…”

Section: Introductionmentioning

confidence: 99%

Calculations of wave excitation and dissipation in Tokamak Chauffage Alfvén wave heating experiment in Brazil

et al. 1999

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The results of numerical calculations of Alfvén wave absorption are discussed for the experimental conditions foreseen for the Tokamak Chauffage Alfvén wave heating experiment in Brazil (TCABR) [Nucl. Fusion 30, 503 (1996)]. In particular, the effect of toroidal mode coupling on the power deposition of Global Alfvén Wave (GAW) eigenmodes is carefully investigated. Resonant absorption of the toroidally coupled sidebands causes a broad power deposition close to the plasma boundary which can surpass the power deposition of the main GAW at the plasma center. However, the wave absorption can be somewhat optimized by a proper choice of mode spectrum. The excitation of a pure mode spectrum centered at the toroidal mode numbers n=−4 and −6 leads to better plasma coupling than a spectrum centered at n=−2. Finally, it is shown that a small population of light impurities in a hydrogen plasma can strongly modify the dispersion of the GAW and the toroidal Alfvén continuum.

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Alfvén waves and rotation of collisional plasmas in tokamaks

Cited by 17 publications

References 12 publications

Induction of poloidal rotation by a radial ponderomotive force of electron cyclotron waves

Induction of poloidal rotation by a radial ponderomotive force of electron cyclotron waves

Anomalous and neoclassical transport suppression by the radial electric field, induced by Alfvén waves in tokamaks

Calculations of wave excitation and dissipation in Tokamak Chauffage Alfvén wave heating experiment in Brazil

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