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Title: Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod

Abstract

In the Alcator C-Mod tokamak, relativistic runaway electron (RE) generation can occur during the flattop current phase of low density, diverted plasma discharges. Due to the high toroidal magnetic field (B0 = 5.4 T), RE synchrotron radiation is measured by a wide-view camera in the visible wavelength range (~400-900 nm). In this paper, a statistical analysis of over one thousand camera images is performed to investigate the plasma conditions under which synchrotron emission is observed in C-Mod. In addition, the spatiotemporal evolution of REs during one particular discharge is explored in detail via a thorough analysis of the distortion-corrected synchrotron images. To accurately predict RE energies, the kinetic solver CODE [Landreman et al 2014 Comput. Phys. Commun. 185 847-855] is used to evolve the electron momentum-space distribution at six locations throughout the plasma: the magnetic axis and flux surfaces q = 1, 4/3, 3/2, 2, and 3. These results, along with the experimentally-measured magnetic topology and camera geometry, are input into the synthetic diagnostic SOFT [Hoppe et al 2018 Nucl. Fusion 58 026032] to simulate synchrotron emission and detection. Interesting spatial structure near the surface q = 2 is found to coincide with the onset of a locked mode andmore » increased MHD activity. Furthermore, the RE density profile evolution is fit by comparing experimental to synthetic images, providing important insight into RE spatiotemporal dynamics.« less

Authors:
; ; ;
Publication Date:
DOE Contract Number:  
FC02-99ER54512
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1880333
DOI:
https://doi.org/10.7910/DVN/SO9QYL

Citation Formats

Tinguely, R. A., Granetz, R. S., Hoppe, M., and Embreus, O. Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod. United States: N. p., 2018. Web. doi:10.7910/DVN/SO9QYL.
Tinguely, R. A., Granetz, R. S., Hoppe, M., & Embreus, O. Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod. United States. doi:https://doi.org/10.7910/DVN/SO9QYL
Tinguely, R. A., Granetz, R. S., Hoppe, M., and Embreus, O. 2018. "Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod". United States. doi:https://doi.org/10.7910/DVN/SO9QYL. https://www.osti.gov/servlets/purl/1880333. Pub date:Tue Dec 04 00:00:00 EST 2018
@article{osti_1880333,
title = {Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod},
author = {Tinguely, R. A. and Granetz, R. S. and Hoppe, M. and Embreus, O.},
abstractNote = {In the Alcator C-Mod tokamak, relativistic runaway electron (RE) generation can occur during the flattop current phase of low density, diverted plasma discharges. Due to the high toroidal magnetic field (B0 = 5.4 T), RE synchrotron radiation is measured by a wide-view camera in the visible wavelength range (~400-900 nm). In this paper, a statistical analysis of over one thousand camera images is performed to investigate the plasma conditions under which synchrotron emission is observed in C-Mod. In addition, the spatiotemporal evolution of REs during one particular discharge is explored in detail via a thorough analysis of the distortion-corrected synchrotron images. To accurately predict RE energies, the kinetic solver CODE [Landreman et al 2014 Comput. Phys. Commun. 185 847-855] is used to evolve the electron momentum-space distribution at six locations throughout the plasma: the magnetic axis and flux surfaces q = 1, 4/3, 3/2, 2, and 3. These results, along with the experimentally-measured magnetic topology and camera geometry, are input into the synthetic diagnostic SOFT [Hoppe et al 2018 Nucl. Fusion 58 026032] to simulate synchrotron emission and detection. Interesting spatial structure near the surface q = 2 is found to coincide with the onset of a locked mode and increased MHD activity. Furthermore, the RE density profile evolution is fit by comparing experimental to synthetic images, providing important insight into RE spatiotemporal dynamics.},
doi = {10.7910/DVN/SO9QYL},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {12}
}

Works referencing / citing this record:

Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod
journal, October 2018