Details

Autor(en) / Beteiligte

• Rognlien, T.D.
• McLean, A.G.
• Fenstermacher, M.E.
• Groth, M.
• Jaervinen, A.E.
• Joseph, I.
• Lasnier, C.J.
• Meyer, W.
• Moser, A.
• Porter, G.D.
• Umansky, M.V.

Titel

Comparison of 2D simulations of detached divertor plasmas with divertor Thomson measurements in the DIII-D tokamak

Ist Teil von

• Nuclear materials and energy, 2017-08, Vol.12, p.44-50

Ort / Verlag

United States: Elsevier Ltd

Erscheinungsjahr

2017

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• •Two-dimensional plasma/neutral transport simulations of the scrape-off-layer/divertor plasma are compared with Divertor Thomson scattering measurements for DIII-D H-mode discharges. Experimental inner/outer divertor plasma and radiation profile asymmetries resulting from changing the direction of the toroidal magnetic field are qualitatively reproduced by the simulations. Steady-state detached plasma solutions are found when increasing the midplane separatrix density beyond a critical value, and that density is within 35% of the experimental measured separatrix density for detachment. The critical density depends on the impurity radiation and pumping models. A modeling study is reported using new 2D data from DIII-D tokamak divertor plasmas and improved 2D transport model that includes large cross-field drifts for the numerically difficult low anomalous transport regime associated with the H-mode. The data set, which spans a range of plasma densities for both forward and reverse toroidal magnetic field (Bt), is provided by divertor Thomson scattering (DTS). Measurements utilizing X-point sweeping give corresponding 2D profiles of electron temperature (Te) and density (ne) across both divertor legs for individual discharges. The simulations focus on the open magnetic field-line regions, though they also include a small region of closed field lines. The calculations show the same features of in/out divertor plasma asymmetries as measured in the experiment, with the normal Bt direction (ion ∇B drift toward the X-point) having higher ne and lower Te in the inner divertor leg than outer. Corresponding emission data for total radiated power shows a strong inner-divertor/outer-divertor asymmetry that is reproduced by the simulations. These 2D UEDGE transport simulations are enabled for steep-gradient H-mode conditions by newly implemented algorithms to control isolated grid-scale irregularities.