Neoclassical transport in strong gradient regions of large aspect ratio tokamaks

Trinczek, Silvia ; Parra, Felix I. ; Catto, Peter J. ; Calvo, Iván ; Landreman, Matt
Issue date: 2023
Creative Commons Attribution 4.0 International (CC BY)
Cite as:
Trinczek, Silvia, Parra, Felix I., Catto, Peter J., Calvo, Iván, & Landreman, Matt. (2023). Neoclassical transport in strong gradient regions of large aspect ratio tokamaks [Data set]. Princeton Plasma Physics Laboratory, Princeton University.
  author      = {Trinczek, Silvia and
                Parra, Felix I. and
                Catto, Peter J. and
                Calvo, Iván and
                Landreman, Matt},
  title       = {{Neoclassical transport in strong gradien
                t regions of large aspect ratio tokamaks
  publisher   = {{Princeton Plasma Physics Laboratory, Pri
                nceton University}},
  year        = 2023,
  url         = {}

We present a new neoclassical transport model for large aspect ratio tokamaks where the gradient scale lengths are of the size of the ion poloidal gyroradius. Previous work on neoclassical transport across transport barriers assumed large density and potential gradients but a small temperature gradient, or neglected the gradient of the mean parallel flow. Using large aspect ratio and low collisionality expansions, we relax these restrictive assumptions. We define a new set of variables based on conserved quantities, which simplifies the drift kinetic equation whilst keeping strong gradients, and derive equations describing the transport of particles, parallel momentum and energy by ions in the banana regime. The poloidally varying parts of density and electric potential are included. Studying contributions from both passing and trapped particles, we show that the resulting transport is dominated by trapped particles. We find that a non-zero neoclassical particle flux requires parallel momentum input which could be provided through interaction with turbulence or impurities. We derive upper and lower bounds for the energy flux across a transport barrier in both temperature and density and present example profiles and fluxes.

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# Filename Filesize
1 ReadMe.txt 526 Bytes
2 Profile and Flux 3.77 KB
3 exact gt.nb 77.7 KB
4 license.txt 3.22 KB