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Title: Experimental characterization of the effect of E×B shear on edge-harmonic oscillation mode structure

Abstract

The Edge Harmonic Oscillation (EHO) mode is one of the characteristic modes that provides an edge transport channel during high-confinement ELM-free phase (the so-called Quiescent High confinement phase). Recent theoretical work and extensive experimental observations have suggested that the large rotational E×B shear is the key to destabilize an EHO. As the eigenmode grows to large amplitude, it will exert a drag on the rotation, resulting in EHO's saturation. However, detailed mechanisms concerning this process remain vague. We have performed here continuous tracking on how the E×B shear affects the EHO mode structure to search for a possible explanation of the saturation mechanism. Two edge density fluctuation diagnostics are employed to observe the eigenmode structure evolution of EHO in the pedestal region in the radial and poloidal directions, respectively. Our results show that the EHO mode's radial wavenumber is strongly correlated with the E×B shear rate, while the poloidal wavenumber is unaffected by the E×B shear rate. During the EHO existence, with the E×B shearing rate ramping down, the radial wavenumber is also observed to be decreasing.

Authors:
ORCiD logo [1];  [1];  [2];  [2];  [3];  [4]; ORCiD logo [4];  [4];  [5];  [6];  [7]
  1. Univ. of California, Davis, CA (United States)
  2. Univ. of California, Davis, CA (United States). Electrical and Computer Engineering
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. General Atomics, San Diego, CA (United States)
  6. General Atomics, San Diego, CA (United States); Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
  7. General Atomics, San Diego, CA (United States). Engineering Physics
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States); Univ. of California, Davis, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1512406
Grant/Contract Number:  
AC02-09CH11466; FC02-04ER54698; SC0012551
Resource Type:
Accepted Manuscript
Journal Name:
Plasma Physics and Controlled Fusion
Additional Journal Information:
Journal Name: Plasma Physics and Controlled Fusion; Journal ID: ISSN 0741-3335
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 42 ENGINEERING

Citation Formats

Chen, Ming, Luo, Chen, Zhu, Yilun, Luhmann, Neville C., Tobias, B. J., Diallo, Ahmed, Kramer, Gerrit J., Ren, Yang, Burrell, Keith H., McKee, George R., and Yan, Zheng. Experimental characterization of the effect of E×B shear on edge-harmonic oscillation mode structure. United States: N. p., 2019. Web. doi:10.1088/1361-6587/ab2174.
Chen, Ming, Luo, Chen, Zhu, Yilun, Luhmann, Neville C., Tobias, B. J., Diallo, Ahmed, Kramer, Gerrit J., Ren, Yang, Burrell, Keith H., McKee, George R., & Yan, Zheng. Experimental characterization of the effect of E×B shear on edge-harmonic oscillation mode structure. United States. doi:10.1088/1361-6587/ab2174.
Chen, Ming, Luo, Chen, Zhu, Yilun, Luhmann, Neville C., Tobias, B. J., Diallo, Ahmed, Kramer, Gerrit J., Ren, Yang, Burrell, Keith H., McKee, George R., and Yan, Zheng. Mon . "Experimental characterization of the effect of E×B shear on edge-harmonic oscillation mode structure". United States. doi:10.1088/1361-6587/ab2174.
@article{osti_1512406,
title = {Experimental characterization of the effect of E×B shear on edge-harmonic oscillation mode structure},
author = {Chen, Ming and Luo, Chen and Zhu, Yilun and Luhmann, Neville C. and Tobias, B. J. and Diallo, Ahmed and Kramer, Gerrit J. and Ren, Yang and Burrell, Keith H. and McKee, George R. and Yan, Zheng},
abstractNote = {The Edge Harmonic Oscillation (EHO) mode is one of the characteristic modes that provides an edge transport channel during high-confinement ELM-free phase (the so-called Quiescent High confinement phase). Recent theoretical work and extensive experimental observations have suggested that the large rotational E×B shear is the key to destabilize an EHO. As the eigenmode grows to large amplitude, it will exert a drag on the rotation, resulting in EHO's saturation. However, detailed mechanisms concerning this process remain vague. We have performed here continuous tracking on how the E×B shear affects the EHO mode structure to search for a possible explanation of the saturation mechanism. Two edge density fluctuation diagnostics are employed to observe the eigenmode structure evolution of EHO in the pedestal region in the radial and poloidal directions, respectively. Our results show that the EHO mode's radial wavenumber is strongly correlated with the E×B shear rate, while the poloidal wavenumber is unaffected by the E×B shear rate. During the EHO existence, with the E×B shearing rate ramping down, the radial wavenumber is also observed to be decreasing.},
doi = {10.1088/1361-6587/ab2174},
journal = {Plasma Physics and Controlled Fusion},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {5}
}

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