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Title: Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod

Abstract

Analysis and modeling of a new set of rotation reversal hysteresis experiments unambiguously show that changes in turbulence are responsible for the intrinsic rotation reversal and the linear to saturated ohmic confinement (LOC/SOC) transition on Alcator C-Mod. Plasmas on either side of the reversal exhibit different toroidal rotation profiles and therefore different turbulence characteristics despite profiles of density and temperature that are indistinguishable within measurement uncertainty. The deactivation of subdominant (in linear growth rate and heat transport) ion-temperature gradient and trapped electron mode-like instabilities in a mixedmode state is identified as the only possible change in turbulence within a quasilinear transport approximation across the reversal which is consistent with the measured profiles and the inferred heat and particle fluxes. This indicates an explanation for the LOC/SOC transition that provides a mechanism for hysteresis through the dynamics of subdominant modes and changes in their relative populations, and does not involve a change in most (linearly) unstable ion-scale drift-wave instability.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [3]; ORCiD logo [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Univ. of California, San Diego, CA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
UC San Diego
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
the Alcator C-Mod Team
OSTI Identifier:
1560064
Grant/Contract Number:  
FG02-04ER54738
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 59; Journal Issue: 10; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma confinement, turbulent transport, tokamaks

Citation Formats

Cao, N. M., Rice, J. E., Diamond, P. H., White, A. E., Baek, S. G., Chilenski, M. A., Hughes, J. W., Irby, J., Reinke, M. L., and Rodriguez-Fernandez, P. Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab3b38.
Cao, N. M., Rice, J. E., Diamond, P. H., White, A. E., Baek, S. G., Chilenski, M. A., Hughes, J. W., Irby, J., Reinke, M. L., & Rodriguez-Fernandez, P. Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod. United States. doi:10.1088/1741-4326/ab3b38.
Cao, N. M., Rice, J. E., Diamond, P. H., White, A. E., Baek, S. G., Chilenski, M. A., Hughes, J. W., Irby, J., Reinke, M. L., and Rodriguez-Fernandez, P. Thu . "Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod". United States. doi:10.1088/1741-4326/ab3b38.
@article{osti_1560064,
title = {Hysteresis as a probe of turbulent bifurcation in intrinsic rotation reversals on Alcator C-Mod},
author = {Cao, N. M. and Rice, J. E. and Diamond, P. H. and White, A. E. and Baek, S. G. and Chilenski, M. A. and Hughes, J. W. and Irby, J. and Reinke, M. L. and Rodriguez-Fernandez, P.},
abstractNote = {Analysis and modeling of a new set of rotation reversal hysteresis experiments unambiguously show that changes in turbulence are responsible for the intrinsic rotation reversal and the linear to saturated ohmic confinement (LOC/SOC) transition on Alcator C-Mod. Plasmas on either side of the reversal exhibit different toroidal rotation profiles and therefore different turbulence characteristics despite profiles of density and temperature that are indistinguishable within measurement uncertainty. The deactivation of subdominant (in linear growth rate and heat transport) ion-temperature gradient and trapped electron mode-like instabilities in a mixedmode state is identified as the only possible change in turbulence within a quasilinear transport approximation across the reversal which is consistent with the measured profiles and the inferred heat and particle fluxes. This indicates an explanation for the LOC/SOC transition that provides a mechanism for hysteresis through the dynamics of subdominant modes and changes in their relative populations, and does not involve a change in most (linearly) unstable ion-scale drift-wave instability.},
doi = {10.1088/1741-4326/ab3b38},
journal = {Nuclear Fusion},
number = 10,
volume = 59,
place = {United States},
year = {2019},
month = {8}
}

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