Momentum transport studies from multi-machine comparisons

Autor: Yoshida, M [ 1 ], Kaye, S [ 2 ], Rice, J [ 3 ], Solomon, W [ 2 ], Tala, T [ 4 ], Bell, RE [ 2 ], Burrell, KH [ 5 ], Ferreira, J [ 6 ], Kamada, Y [ 1 ], McDonald, D [ 7,8 ], Mantica, P [ 9 ], Podpaly, Y [ 3 ], Reinke, ML [ 3 ], Sakamoto, Y [ 1 ], Salmi, A [ 4 ], ITPA Transport, Confinement Topical Group
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: ITPA Transport & Confinement Topical Group 2012, ' Momentum transport studies from multi-machine comparisons ', Nuclear Fusion, vol. 52, no. 12, 123005 . https://doi.org/10.1088/0029-5515/52/12/123005
Nuclear fusion (Online) 52 (2012): 123005. doi:10.1088/0029-5515/52/12/123005
info:cnr-pdr/source/autori:Yoshida, M [ 1 ] ; Kaye, S [ 2 ] ; Rice, J [ 3 ] ; Solomon, W [ 2 ] ; Tala, T [ 4 ] ; Bell, RE [ 2 ] ; Burrell, KH [ 5 ] ; Ferreira, J [ 6 ] ; Kamada, Y [ 1 ] ; McDonald, D [ 7,8 ] ; Mantica, P [ 9 ] ; Podpaly, Y [ 3 ] ; Reinke, ML [ 3 ] ; Sakamoto, Y [ 1 ] ; Salmi, A [ 4 ]; and ITPA Transport & Confinement Topical Group/titolo:Momentum transport studies from multi-machine comparisons/doi:10.1088%2F0029-5515%2F52%2F12%2F123005/rivista:Nuclear fusion (Online)/anno:2012/pagina_da:123005/pagina_a:/intervallo_pagine:123005/volume:52
ISSN: 1741-4326
0029-5515
DOI: 10.1088/0029-5515/52/12/123005
Popis: A database of toroidal momentum transport on five tokamaks, Alcator C-Mod, DIII-D, JET, NSTX and JT-60U, has been constructed under a wide range of conditions in order to understand the characteristics of toroidal momentum transport coefficients, namely the toroidal momentum diffusivity (χ φ ) and the pinch velocity (V pinch). Through an inter-machine comparison, the similarities and differences in the properties of χ φ and V pinch among the machines have been clarified. Parametric dependences of these momentum transport coefficients have been investigated over a wide range of plasma parameters taking advantage of the different operation regimes in machines. The approach offers insights into the parametric dependences as follows. The toroidal momentum diffusivity (χ φ ) generally increases with increasing heat diffusivity (χ i). The correlation is observed over a wide range of χ φ , covering roughly two orders of magnitude, and within each of the machines over the whole radius. Through the inter-machine comparison, it is found that χ φ becomes larger in the outer region of the plasma. Also observed is a general trend for V pinch in tokamaks; the inward pinch velocity (−V pinch) increases with increasing χ φ . The results that are commonly observed in machines will support a toroidal rotation prediction in future devices. On the other hand, differences among machines have been observed. The toroidal momentum diffusivity, χ φ , is larger than or equal to χ i in JET and JT-60U; on the other hand, χ φ is smaller than or equal to χ i in NSTX, DIII-D and Alcator C-Mod. In DIII-D, the ratio −RV pinch/χ φ at r/a = 0.5–0.6 is about 2, which is small compared with that in other tokamaks (−RV pinch/χ φ ≈ 5). Based on these different observations, parametric dependences of χ φ /χ i, RV pinch/χ φ and χ φ have been investigated in H-mode plasmas. Across the dataset from all machines, the ratio χ φ /χ i tends to be larger in low at fixed T e/T i and . An increase in χ φ is observed with decreasing n e and/or increasing T e. The pinch number (−RV pinch/χ φ ) is observed to increase with increasing at both q 95 = 5.5–7.2 and q 95 = 3.7–4.5. Here , , T e, T i, and q 95 are, respectively, the normalized effective electron collision frequency, the normalized ion poloidal Larmor radius, the electron and ion temperatures, the inverse ratio of density scale length, , to the major radius, R, and the safety factor at the 95% flux surface.
Databáze: OpenAIRE
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