Kinetic effects on a tokamak pedestal ion flow, ion heat transport and bootstrap current
Plasma Physics and Controlled Fusion 55:4 (2013)
Abstract:
We consider the effects of a finite radial electric field on ion orbits in a subsonic pedestal. Using a procedure that makes a clear distinction between a transit average and a flux surface average we are able to solve the kinetic equation to retain the modifications due to finite E→ × B→ drift orbit departures from flux surfaces. Our approach properly determines the velocity space localized, as well as the nonlocal, portion of the ion distribution function in the banana and plateau regimes in the small aspect ratio limit. The rapid variation of the poloidal ion flow coefficient and the electrostatic potential in the total energy modify previous banana regime evaluations of the ion flow, the bootstrap current, and the radial ion heat flux in a subsonic pedestal. In the plateau regime, the rapid variation of the poloidal flow coefficient alters earlier results for the ion flow and bootstrap current, while leaving the ion heat flux unchanged since the rapid poloidal variation of the total energy was properly retained. © 2013 IOP Publishing Ltd.Turbulent momentum pinch of diamagnetic flows in a tokamak
ArXiv 1301.426 (2013)
Abstract:
The ion toroidal rotation in a tokamak consists of an $E\times B$ flow due to the radial electric field and a diamagnetic flow due to the radial pressure gradient. The turbulent pinch of toroidal angular momentum due to the Coriolis force studied in previous work is only applicable to the $E\times B$ flow. In this Letter, the momentum pinch for the rotation generated by the radial pressure gradient is calculated and is compared with the Coriolis pinch. This distinction is important for subsonic flows or the flow in the pedestal where the two types of flows are similar in size and opposite in direction. In the edge, the different pinches due to the opposite rotations can result in intrinsic momentum transport that gives significant rotation peaking.Electron flow driven instability in finite beta plasmas
40th EPS Conference on Plasma Physics, EPS 2013 2 (2013) 1098-1101
Long-wavelength limit of second-order gyrokinetics and the intrinsic ambipolarity of the turbulent tokamak
39th EPS Conference on Plasma Physics 2012, EPS 2012 and the 16th International Congress on Plasma Physics 1 (2012) 433-436
Analytic fluid theory of beam spiraling in high-intensity cyclotrons
ArXiv 1210.1175 (2012)