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Title: Multi-field/-scale interactions of turbulence with neoclassical tearing mode magnetic islands in the DIII-D tokamak

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4977533· OSTI ID:1372473

We present the first localized measurements of long and intermediate wavelength turbulent density fluctuations ($$\sim\atop{n}$$) and long wavelength turbulent electron temperature fluctuations ($$\sim\atop{T}$$e) modified by m/n = 2/1 Neoclassical Tearing Mode (NTM) islands (m and n are the poloidal and toroidal mode numbers, respectively). These long and intermediate wavelengths correspond to the expected Ion Temperature Gradient and Trapped Electron Mode scales, respectively. Two regimes have been observed when tracking $$\sim\atop{n}$$ during NTM evolution: (1) small islands are characterized by a steep Te radial profile and turbulence levels comparable to those of the background; (2) large islands have a flat Te profile and reduced turbulence level at the O-point. Radially outside the large island, the Te profile is steeper and the turbulence level increased compared to the no or small island case. Reduced turbulence at the O-point compared to the X-point leads to a 15% modulation of $$\sim\atop{n}$$2 across the island that is nearly in phase with the Te modulation. Qualitative comparisons to the GENE non-linear gyrokinetic code are promising with GENE replicating the observed scaling of turbulence modification with island size. Furthermore, these results are significant as they allow the validation of gyrokinetic simulations modeling the interaction of these multi-scale phenomena.

Research Organization:
General Atomics, San Diego, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
FC02-04ER54698; FG02-08ER54984; FG03-86ER53266; SC0016073; AC02-05CH11231; S014889-R
OSTI ID:
1372473
Alternate ID(s):
OSTI ID: 1348028
Journal Information:
Physics of Plasmas, Vol. 24, Issue 5; ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 38 works
Citation information provided by
Web of Science

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Impact of neoclassical tearing mode–turbulence multi-scale interaction in global confinement degradation and magnetic island stability journal December 2017
A neoclassical drift-magnetohydrodynamical fluid model of the interaction of a magnetic island chain with a resonant error-field in a high temperature tokamak plasma journal April 2018
Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas journal January 2019
Interaction of magnetic islands with turbulent electron temperature fluctuations in DIII-D and in GENE nonlinear gyrokinetic simulations journal December 2019
Experimental identification of nonlinear coupling between (intermediate, small)-scale microturbulence and an MHD mode in the core of a superconducting tokamak journal November 2017
Influence of m  /  n = 2/1 magnetic islands on perpendicular flows and turbulence in HL-2A Ohmic plasmas journal December 2017
The impact of an m / n   =  2/1 locked mode on the disruption process during a massive gas injection shutdown on J-TEXT journal August 2019
LH transition trigger physics in ITER-similar plasmas with applied n   =  3 magnetic perturbations journal September 2019
Controlled neoclassical tearing mode (NTM) healing by fueling pellets and its impact on electron cyclotron current drive requirements for complete NTM stabilization journal October 2019
Control of neoclassical tearing mode by synergetic effects of resonant magnetic perturbation and electron cyclotron current drive in reversed magnetic shear tokamak plasmas journal January 2020