Skip to main content

Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment

Publication ,  Journal Article
Ren, Y; Wang, WX; LeBlanc, BP; Guttenfelder, W; Kaye, SM; Ethier, S; Mazzucato, E; Lee, KC; Domier, CW; Bell, R; Smith, DR; Yuh, H
Published in: Physics of Plasmas
November 1, 2015

In this letter, we report the first observation of the fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)]. The observation was made in a set of RF-heated L-mode plasmas with toroidal magnetic field of 0.55 T and plasma current of 300 kA. It is observed that electron-scale turbulence spectral power (measured with a high-k collective microwave scattering system) decreases significantly following fast cessation of RF heating that occurs in less than 200 μs. The large drop in the turbulence spectral power has a short time delay of about 1-2 ms relative to the RF cessation and happens on a time scale of 0.5-1 ms, much smaller than the energy confinement time of about 10 ms. Power balance analysis shows a factor of about 2 decrease in electron thermal diffusivity after the sudden drop of turbulence spectral power. Measured small changes in equilibrium profiles across the RF cessation are unlikely able to explain this sudden reduction in the measured turbulence and decrease in electron thermal transport, supported by local linear stability analysis and both local and global nonlinear gyrokinetic simulations. The observations imply that nonlocal flux-driven mechanism may be important for the observed turbulence and electron thermal transport.

Duke Scholars

Published In

Physics of Plasmas

DOI

EISSN

1089-7674

ISSN

1070-664X

Publication Date

November 1, 2015

Volume

22

Issue

11

Related Subject Headings

  • Fluids & Plasmas
  • 0203 Classical Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
  • 0201 Astronomical and Space Sciences
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Ren, Y., Wang, W. X., LeBlanc, B. P., Guttenfelder, W., Kaye, S. M., Ethier, S., … Yuh, H. (2015). Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment. Physics of Plasmas, 22(11). https://doi.org/10.1063/1.4935113
Ren, Y., W. X. Wang, B. P. LeBlanc, W. Guttenfelder, S. M. Kaye, S. Ethier, E. Mazzucato, et al. “Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment.” Physics of Plasmas 22, no. 11 (November 1, 2015). https://doi.org/10.1063/1.4935113.
Ren Y, Wang WX, LeBlanc BP, Guttenfelder W, Kaye SM, Ethier S, et al. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment. Physics of Plasmas. 2015 Nov 1;22(11).
Ren, Y., et al. “Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment.” Physics of Plasmas, vol. 22, no. 11, Nov. 2015. Scopus, doi:10.1063/1.4935113.
Ren Y, Wang WX, LeBlanc BP, Guttenfelder W, Kaye SM, Ethier S, Mazzucato E, Lee KC, Domier CW, Bell R, Smith DR, Yuh H. Fast response of electron-scale turbulence to auxiliary heating cessation in National Spherical Torus Experiment. Physics of Plasmas. 2015 Nov 1;22(11).

Published In

Physics of Plasmas

DOI

EISSN

1089-7674

ISSN

1070-664X

Publication Date

November 1, 2015

Volume

22

Issue

11

Related Subject Headings

  • Fluids & Plasmas
  • 0203 Classical Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
  • 0201 Astronomical and Space Sciences