148 0

Effects of LHRF on toroidal rotation in Alcator C-Mod plasmas

Title
Effects of LHRF on toroidal rotation in Alcator C-Mod plasmas
Author
이정표
Keywords
NO MOMENTUM INPUT; TOKAMAK PLASMA; DIII-D; CYCLOTRON; TRANSPORT; FREQUENCY; JET
Issue Date
2013-08
Publisher
IOP Publishing; IAEA
Citation
Nuclear Fusion. (Nuclear Fusion, September 2013, 53(9), P.093015
Abstract
Application of lower hybrid range of frequencies (LHRF) waves can induce both co- and counter-current directed changes in toroidal rotation in Alcator C-Mod plasmas, depending on the target plasma current, electron density, confinement regime and magnetic shear. For ohmic L-mode discharges with good core LH wave absorption, and significant current drive at a fixed LH power near 0.8 MW, the interior (r/a < 0.5) rotation increments (on a time scale of order the current relaxation time) in the counter-current direction if n(e)(10(20) m(-3)) > q(95)/11.5, and in the co-current direction if n(e)(10(20) m(-3)) < q(95)/11.5. All discharges with co-current rotation changes have q(0) > 1, indicating a good correlation with driven current fraction, unifying the results observed on various tokamaks. For high density (n(e) >= 1.2 x 10(20) m(-3)) L-mode target discharges, where core LH wave absorption is low, the rotation change is in the co-current direction, but evolves on a shorter momentum transport time scale, and is seen across the entire spatial profile. For H-mode target plasmas, both co- and counter-current direction increments have been observed with LHRF. The H-mode co-rotation is correlated with the pedestal temperature gradient, which itself is enhanced by the LH waves absorbed in the plasma periphery. The H-mode counter-rotation increment, a flattening of the peaked velocity profile in the core, is consistent with a reduction in the momentum pinch correlated with a steepening of the core density profile. Most of these rotation changes must be due to indirect transport effects of LH waves on various parameters, which modify the momentum flux.
URI
http://iopscience.iop.org/article/10.1088/0029-5515/53/9/093015/metahttp://hdl.handle.net/20.500.11754/45230
ISSN
0029-5515
DOI
10.1088/0029-5515/53/9/093015
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > NUCLEAR ENGINEERING(원자력공학과) > Articles
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE