Abstract Details
Abstracts
Author: Silvia Trinczek
Requested Type: Consider for Invited
Submitted: 2023-03-18 19:55:15
Co-authors: F. I. Parra, P. J. Catto, I. Calvo, M. Landreman
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Road
Princeton, New Jersey 08540
United States
Abstract Text:
We present a new model to describe neoclassical transport in strong gradient regions in tokamaks such as internal transport barriers and the pedestal [1]. Previous work on neoclassical transport across transport barriers assumed large density and potential gradients but a small temperature gradient [2], or neglected the gradient of the mean parallel flow [3]. Using a large aspect ratio and low collisionality expansion, we relax these restrictive assumptions and keep gradient scale lengths that are of the size of the ion poloidal gyroradius. The poloidally varying parts of density and electric potential are included. We derive equations describing the transport of particles, parallel momentum and energy by ions in the banana regime. Studying contributions from both passing and trapped particles, we show that the resulting transport is dominated by trapped particles but includes the poloidal variations in the electric potential caused by passing particles. We find that a non-zero neoclassical particle flux requires parallel momentum input which could be provided through interaction with turbulence or impurities. The neoclassical energy flux across a transport barrier has upper and lower bounds in both temperature and density. Solutions to our transport equations are highly sensitive to the choice of sources and boundary conditions and do not always exist.
[1] S. Trinczek, F. I. Parra, P. J. Catto, I. Calvo, M. Landreman, arXiv:2301.07080 (2023)
[2] P. J. Catto, F. I. Parra, et al., Plasma Phys. Control. Fusion 55, 045009 (2013)
[3] K. C. Shaing, C. T. Hsu, Physics of Plasmas 19, 022502 (2012)
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