RT Journal Article
T1 The impact of rational surfaces on radial heat transport in TJ-II
A1 Van Milligen, B.Ph.
A1 Hernández Nicolau, Javier
A1 García Gonzalo, Luis
A1 Carreras Verdaguer, Benjamin Andres
A1 Hidalgo, C.
AB In this work, we study the outward propagation of temperature perturbations. For this purpose, we apply an advanced analysis technique, transfer entropy, to ECE measurements performed in ECR heated discharges at the low-shear stellarator TJ-II. We observe that the propagation of these perturbations is not smooth, but is slowed down at specific radial positions, near 'trapping zones' characterized by long time lags with respect to the perturbation origin. We also detect instances of rapid or instantaneous (non-local) propagation, in which perturbations appear to 'jump over' specific radial regions. The analysis of perturbations introduced in a resistive magneto-hydrodynamic model of the plasma leads to similar results. The radial regions corresponding to slow radial transport are identified with maxima of the flow shear associated with rational surfaces (mini-transport barriers). The non-local interactions are ascribed to MHD mode coupling effects.
PB IOP Publishing
SN 0029-5515
YR 2017
FD 2017-05
LK https://hdl.handle.net/10016/32559
UL https://hdl.handle.net/10016/32559
LA eng
NO Autor colectivo: TJ-II Team
DS e-Archivo
RD 27 jul. 2024