Collisionality driven turbulent particle transport changes in DIII-D H-mode plasmas
Journal article, 2020

The results of the experimental dimensionless scan in this paper confirm that there is an increase in density peaking towards lower collisionality and that this can be partly linked to a shift in the turbulence regime from ITG towards TEM. However at the lowest collisionality, the changes in turbulence and transport are much more pronounced than expected from direct collisionality effect on the turbulence. In this paper, the collisionality, ν ∗ is varied by a factor 5, while keeping ρ ∗, q, β, M, fixed. Additionally, a 3 Hz gas puff modulation is applied to modulate the electron density profile and extract the perturbed transport coefficients using two diagnostics. The transport analysis shows that the increase in density peaking at low ν ∗ is linked to an increase in the inward particle pinch and not an increase in core fueling. These observations are not only in agreement with prior modeling scans of how turbulence changes as a function of collisionality and its impact upon the particle fluxes, but also with the multi-machine database (Fable E. et al 2010 Plasma Phys. Control. Fusion 52 015007) (Angioni C. et al 2003 Phys. Rev. Lett. 90 205003). The changes in turbulence across the collisionality scan were captured at large scale by the BES and at smaller scale by the DBS. A comparison with gradient-driven GENE simulations showed similar trends at both scales. Moreover, the changes observed in overall transport are in agreement with gradient-driven TGLF particle flux simulations. This indicates that TGLF/GENE when given the gradients as input, are able to reproduce the experimentally observed turbulence changes.

collisionality

tokamak

transport

turbulence

Author

S. Mordijck

The College of William and Mary

T. L. Rhodes

University of California

L. Zeng

University of California

A. Salmi

Technical Research Centre of Finland (VTT)

T. Tala

Technical Research Centre of Finland (VTT)

C. C. Petty

General Atomics

G. R. McKee

University of Wisconsin Madison

R. Reksoatmodjo

The College of William and Mary

Fredrik Eriksson

Condensed Matter and Materials Theory

Erik Fransson

Condensed Matter and Materials Theory

Hans Nordman

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Plasma Physics and Fusion Energy

Nuclear Fusion

0029-5515 (ISSN)

Vol. 60 6 066019

Subject Categories

Fusion, Plasma and Space Physics

DOI

10.1088/1741-4326/ab81aa

More information

Latest update

6/30/2020