Hyperviscosity of a magnetized plasma

Mikhaǐlovskiǐ, A. B.; Коновалов, С. В.; Tsypin, V. S.

doi:10.1134/1.1364718

Cited by 18 publications

(32 citation statements)

References 6 publications

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“…This has allowed us to obtain the necessary condition for intrinsically ambipolar particle transport in such a field, given by Eq. (30), which agrees with the arbitrary-collisionality result of Ref. [16].…”

Section: Discussionsupporting

confidence: 81%

“…This problem is not new and has been studied in Refs. [29][30][31][32][33][34], but none of these treatments is completely satisfactory. As discussed in the Appendix of this paper, Ref.…”

Section: Introductionmentioning

confidence: 99%

“…Reference [30] only considered a large-aspect-ratio rippled tokamak and neglected cross-field ion viscosity, and was therefore unable to describe the axisymmetric limit and consequently the case of small toroidal field ripple. Calculations based on the moment approach to neoclassical theory [31,35] cannot exactly recover the correct expression for the parallel ion flow velocity, which was first calculated by Hazeltine [36] in the axisymmetric tokamak case and in this paper for an arbitrary toroidal geometry.…”

Section: Introductionmentioning

confidence: 99%

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Neoclassical momentum transport in a collisional stellarator and a rippled tokamak

Simakov

Helander

2009

Physics of Plasmas

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Short mean-free path two-fluid equations are employed to evaluate the lowest order non-ambipolar radial current in plasma confined by a three-dimensional toroidal magnetic field. The result is used to obtain a necessary condition for intrinsic ambipolarity of plasma transport in such a field and to derive a criterion for the importance of the toroidal field ripple for collisional tokamak plasma rotation. The ripple effects on toroidal plasma rotation are found to be negligible if the characteristic perpendicular length scale is determined by the pedestal width of order the poloidal ion gyroradius (as may be the case in the H-mode regime), but may conceivably become important for more shallow plasma gradients.

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Section: Discussionsupporting

confidence: 81%

“…This problem is not new and has been studied in Refs. [29][30][31][32][33][34], but none of these treatments is completely satisfactory. As discussed in the Appendix of this paper, Ref.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Neoclassical momentum transport in a collisional stellarator and a rippled tokamak

Simakov

Helander

2009

Physics of Plasmas

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“…A parallel particle flux arises on B as a consequence of the heat flux on A, and since this heat flux is related to the radial temperature gradient by neoclassical theory, such a gradient drives plasma rotation. A similar heat-flux-driven contribution to the viscosity arises in a fully ionized plasma flowing at a speed comparable to the diamagnetic velocity [29,30] and can be interpreted in similar terms.…”

Section: Effect Of An External Momentum Sourcementioning

confidence: 86%

Controlling edge plasma rotation through poloidally localized refueling

2003

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The transport of angular momentum due to neutral atoms in the tokamak edge is calculated and shown to be sensitive to the poloidal location of the neutrals. In the absence of external momentum sources, the edge plasma is predicted to rotate spontaneously in the opposite direction to the plasma current, at a speed proportional to the radial ion temperature gradient. If the plasma is collisional, this counter-current rotation is largest if the neutrals are concentrated on the inboard side of the torus, while the opposite holds in a collisionless plasma. The presence of heavy impurity ions also promotes counter-current rotation. The rotation caused by an external momentum source, such as neutral-beam injection, is found to be larger when the neutrals are on the inboard rather than the outboard side.

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“…Here, η 2 = 1.2m i n i ρ 2 i ν ii is the second Braginskii transverse viscosity coefficient, F rip = m i n i χ φ U φ is the ripple friction [29] where χ φ = 1.25(N r δ 2 v Ti /R 0 ), N r is the number of ripples and δ is ripple modulation of the toroidal magnetic field, and F φ,cx = m i n i n n σ v cx U φ is the charge exchange friction force. Usually, the ripple modulation is very small in tokamaks and the toroidal friction is mainly defined by the charge exchange frictional force that is well known from neutral beam heating experiments (see, e.g.…”

Section: Toroidal Velocitymentioning

confidence: 99%

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

et al. 2004

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The profile and dissipation of the field excited by dynamic ergodic divertor (DED) coils in tokamak plasmas are calculated, and an estimate is made of the poloidal/toroidal velocities driven by this field. The coils are idealized as an inboard sheet current composed of a toroidal sequence of helical line current segments expanded in Fourier series with poloidal/toroidal mode numbers M/N, and mode amplitudes depending on feeding. Numerical calculations with cylindrical and toroidal codes show maxima of field dissipation due to Alfvén wave mode conversion effect taking place at the rational magnetic surfaces where q = M/N. The effects of toroidicity and ion collisions in the dielectric tensor in the upper DED frequency range described (f = 5-10 kHz) are found to be very important in absorption calculations. At the q = 3 resonant magnetic surface typical for DED coil design, it is estimated that ponderomotive forces produced by 20 kW of dissipation can drive local toroidal and poloidal flows of respective orders 8 km s −1 and 10 km s −1 in the TEXTOR tokamak.

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Hyperviscosity of a magnetized plasma

Cited by 18 publications

References 6 publications

Neoclassical momentum transport in a collisional stellarator and a rippled tokamak

Neoclassical momentum transport in a collisional stellarator and a rippled tokamak

Controlling edge plasma rotation through poloidally localized refueling

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

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