Neoclassical physics in full distribution function gyrokinetics

Dif‐Pradalier, G.; Diamond, P. H.; Grandgirard, V.; Sarazin, Y.; Abiteboul, J.; Garbet, X.; Ghendrih, Philippe; Latu, Guillaume; Strugarek, Antoine; Ku, S.; Chang, C. S.

doi:10.1063/1.3592652

Cited by 40 publications

(44 citation statements)

References 85 publications

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“…The right-hand side of (1) contains the collision operator C(F ), which is implemented im Gysela as a Fokker-Planck type operator acting on v G only. This operator conserves density, momentum and energy, and it was demonstrated that it allows one to recover the main results of neoclassical theory, in particular concerning the predictions for heat transport and poloidal rotation, including their dependence on aspect ratio and collisionality [23]. Additionally, the source term S provides a constant input of heat in the system.…”

Section: Flux-driven Simulations With the Gyrokinetic Code Gyselamentioning

confidence: 99%

Turbulent momentum transport in core tokamak plasmas and penetration of scrape-off layer flows

Abiteboul

Ghendrih

Grandgirard

et al. 2013

Plasma Phys. Control. Fusion

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Abstract. The turbulent transport of toroidal angular momentum in the core of a tokamak plasma is investigated in global, full-f gyrokinetic simulations, performed with the GYSELA code in the flux-driven regime. During the initial turbulent phase, a front of positive Reynolds stress propagates radially, generating intrinsic toroidal rotation from a vanishing initial profile. This is also accompanied by a propagating front of turbulent heat flux. In the statistical steady-state regime, turbulent transport exhibits large-scale avalanche-like events which are found to transport both heat and momentum, and similar statistical properties are obtained for both fluxes. The impact of scrape-off layer flows is also investigated by modifying the boundary conditions in the simulations. The observed impact is radially localized for L-mode like poloidal profiles of parallel velocity at the edge, while a constant velocity at the edge can modify the core toroidal rotation profile in a large fraction of the radial domain.

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Section: Flux-driven Simulations With the Gyrokinetic Code Gyselamentioning

confidence: 99%

Turbulent momentum transport in core tokamak plasmas and penetration of scrape-off layer flows

Abiteboul

Ghendrih

Grandgirard

et al. 2013

Plasma Phys. Control. Fusion

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“…In both codes, only the ion distribution functions are calculated and electrons are assumed to respond adiabatically to the electric potential on a flux surface. Coulomb collisions are not included in the XGC1p simulations, while a Fokker-Planck operator acting on v is included in Gysela [20]. The collisionality ν * = 0.1 and the total simulation time is roughly 0.3 collision time for Gyselasimulation.…”

Section: Simulation Approach and Momentum Conservationmentioning

confidence: 99%

Physics of intrinsic rotation in flux-driven ITG turbulence

Ku¹,

Abiteboul²,

Diamond³

et al. 2012

Nucl. Fusion

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Abstract. Global, heat flux-driven ITG gyrokinetic simulations which manifest the formation of macroscopic, mean toroidal flow profiles with peak thermal Mach number 0.05, are reported. Both a particle-in-cell (XGC1p) and a semi-Lagrangian (Gysela) approach are utilized without a priori assumptions of scale-separation between turbulence and mean fields. Flux-driven ITG simulations with different edge flow boundary conditions show in both approaches the development of net unidirectional intrinsic rotation in the co-current direction. Intrinsic torque is shown to scale approximately linearly with the inverse scale length of the ion temperature gradient. External momentum input is shown to effectively cancel the intrinsic rotation profile, thus confirming the existence of a local residual stress and intrinsic torque. Fluctuation intensity, intrinsic torque and mean flow are demonstrated to develop inwards from the boundary. The measured correlations between residual stress and two fluctuation spectrum symmetry breakers, namely E × B shear and intensity gradient, are similar. Avalanches of (positive) heat flux, which propagate either outwards or inwards, are correlated with avalanches of (negative) parallel momentum flux, so that outward transport of heat and inward transport of parallel momentum are correlated and mediated by avalanches. The probability distribution functions of the outward heat flux and the inward momentum flux show strong structural similarity.

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“…Here K 1 is formed by evaluating the impurity concentration and parallel viscous matrix elements. Calculations of the coefficient K 1 can be done analytically [19], numerically [35,36], or determined from plasma simulations [37,38,39].…”

Section: Neoclassical Theorymentioning

confidence: 99%

Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Grierson¹,

Burrell²,

Solomon³

et al. 2013

Nucl. Fusion

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Abstract. In tokamak plasmas with low levels of toroidal rotation, the radial electric field E r is a combination of pressure gradient and toroidal and poloidal rotation components, all having similar magnitudes. In order to assess the validity of neoclassical poloidal rotation theory for determining the poloidal rotation contribution to E r , D α emission from neutral beam heated tokamak discharges in DIII-D [J.L. Luxon, Nucl. Fusion 42, 614 (2002)] has been evaluated in a sequence of low torque (electron cyclotron resonance heating and balanced diagnostic neutral beam pulse) discharges to determine the local deuterium toroidal rotation velocity. By invoking the radial force balance relation the deuterium poloidal rotation can be inferred. It is found that the deuterium poloidal flow exceeds the neoclassical value in plasmas with collisionality ν * i < 0.1, being more ion diamagnetic, and with a stronger dependence on collisionality than neoclassical theory predicts. At low toroidal rotation, the poloidal rotation contribution to the radial electric field and its shear is significant. The effect of anomalous levels of poloidal rotation on the radial electric field and cross-field heat transport is investigated for ITER parameters.

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Neoclassical physics in full distribution function gyrokinetics

Cited by 40 publications

References 85 publications

Turbulent momentum transport in core tokamak plasmas and penetration of scrape-off layer flows

Turbulent momentum transport in core tokamak plasmas and penetration of scrape-off layer flows

Physics of intrinsic rotation in flux-driven ITG turbulence

Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

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