Speaker
Mr
Manaure Francisquez
(Dartmouth College)
Description
A study of L and H mode-like plasma turbulence in the edge of tokamaks is presented, with an emphasis on characterization of these plasmas in numerical simulations with a new Global Drift-Ballooning (GDB) model. This work employs drift-reduced Braginskii two-fluid equations for electromagnetic low-frequency turbulence and solves them in a global large-aspect ratio annulus centered on the last closed flux-surface (LCFS) as an approximation of small to medium-size tokamaks. The simulations include plasma sources at the inner edge of the pedestal region as well as a limiter region in the Scrape-Off-Layer (SOL) and evolves self-consistently the density, temperature, and ExB shear profiles on the transport time-scale. GDB is able to generate both L and H mode-like plasmas with realistic parameters. L-mode transport appears to be largely driven by resistive-ballooning structures, in the presence of a balance between ExB and the ion-diamagnetic drifts. Pressure profiles also appear to exhibit a near-SOL breakpoint that Mirror Langmuir Probes (MLP) detect in C-Mod, postulated to separate Drift Wave (DW) like and RB-like fluctuations. Separate simulations carried out with H-mode parameters develop improved confinement, $E_r$ wells at the LCFS and spontaneous generation of temperature pedestals with density pedestals remaining absent up to times in the order of 0.2 ms. Candidate first-principles explanations to the modification of the electric field profile are discussed.
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, under Award Number DE-SC0010508.
| Country or International Organization | United States of America |
|---|---|
| Paper Number | TH/P2-29 |
Primary author
Mr
Manaure Francisquez
(Dartmouth College)
Co-authors
Mr
Barrett Rogers
(Dartmouth College)
Mr
Zhu Ben
(Dartmouth College)
