Transport of parallel momentum by collisionless drift wave turbulence

Abstract

This paper presents a novel, unified approach to the theory of turbulent transport of parallel momentum by collisionless drift waves. The physics of resonant and nonresonant off-diagonal contributions to the momentum flux is emphasized, and collisionless momentum exchange between waves and particles is accounted for. Two related momentum conservation theorems are derived. These relate the resonant particle momentum flux, the wave momentum flux, and the refractive force. A perturbative calculation, in the spirit of Chapman–Enskog theory, is used to obtain the wave momentum flux, which contributes significantly to the residual stress. A general equation for mean k∥ (⟨k∥⟩) is derived and used to develop a generalized theory of symmetry breaking. The resonant particle momentum flux is calculated, and pinch and residual stress effects are identified. The implications of the theory for intrinsic rotation and momentum transport bifurcations are discussed.

Poloidal rotation and its relation to the potential vorticity flux

“…I, the sensitivity of the mean flow to the forcing and dissipation profile can be understood to follow as a result of the emission and absorption of wave momentum in regions above and below marginality ͑respectively͒. In this context it is natural to consider whether an analogous result can be obtained via the consideration of a Poynting theorem for wave momentum, 11,55,56 i.e.,…”

Conversion of poloidal flows into toroidal flows by phase space structures in trapped ion resonance driven turbulence

“…[7,8,9] To elaborate this point, it is useful to recall that toroidal flow evolution equation generally takes the form:…”

“…Here χ ζ is the anomalous viscosity, V pinch is the pinch [31,32,33], Π res rζ is the residual stress [7,8,9], and a is a parallel acceleration [7,34] which acts as a local source. Π res rζ and a are required to spin-up plasmas from rest [8,9].…”

“…Here, the first is the momentum flux carried by resonant particles, the second is the momentum flux carried by drift wave turbulence [7], the third term is the polarization stress [35,36], and the fourth is the projection of perpendicular force [37], or equivalently, the J ×B torque. The first term, i.e.…”

“…The first term, i.e. the momentum flux due to resonant particles can have two contributions, both from quasilinear like flux [7] and from dynamical friction, can form in turbulence due to strong wave-particle resonance, such as trapped ion or trapped electron precession resonances. Relevant applications to toroidal momentum transport phenomenology, e.g.…”