Non-neoclassical up/down asymmetry of impurity emission on Alcator C-Mod

被引：16

作者：

Reinke, M. L. ^{[1
]}

Rice, J. E. ^{[1
]}

Hutchinson, I. H. ^{[1
]}

Greenwald, M. ^{[1
]}

Howard, N. T. ^{[1
]}

Hughes, J. W. ^{[1
]}

Irby, J. ^{[1
]}

Podpaly, Y. ^{[1
]}

Terry, J. L. ^{[1
]}

White, A. ^{[1
]}

机构：

[1] MIT, Plasma Sci & Fus Ctr, Cambridge, MA 02139 USA

来源：

NUCLEAR FUSION | 2013年 / 53卷 / 04期

关键词：

POLOIDAL ASYMMETRIES; ZONAL FLOWS; SPECTRA; TOMOGRAPHY; PLASMA; ARGON; EDGE;

D O I：

10.1088/0029-5515/53/4/043006

中图分类号：

O35 [流体力学]; O53 [等离子体物理学];

学科分类号：

070204 ; 080103 ; 080704 ;

摘要：

We demonstrate that existing theories are insufficient to explain up/down asymmetries of argon x-ray emission in Alcator C-Mod ohmic plasmas. Instead of the poloidal variation, (n) over tilde (z)/< n(z)>, being of order the inverse aspect ratio, is an element of, and scaling linearly with B-t(n) over bar (e)/I-p(2), it is observed over 0.8 < r/a < 1.0 to be of order unity and exhibits a threshold behaviour between 3.5 B-t<(n) over bar (e)/I-p < 4.0 (T10(20) m(-3) MA(-1)). The transition from a poloidally symmetric to asymmetric impurity distribution is shown to occur at densities just below those that trigger a reversal of the core toroidal rotation direction, thought to be linked to the transition between the linear and saturated ohmic confinement regimes. A possible drive is discussed by which anomalous radial transport might sustain the impurity density asymmetry as the ratio of the perpendicular to parallel equilibration times, tau(perpendicular to),(z)/tau(parallel to,z), approaches unity. This explanation requires a strong up/down asymmetry in radial flux which, while not observable on C-Mod, has been measured in TEXT and Tore Supra ohmic plasmas.

引用

页数：10

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