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Title: Effects of two-dimensional magnetic uncertainties and three-dimensional error and perturbation fields on the Small Angle Slot divertor geometry and topology [Effects of two- and three-dimensional magnetic fields on the Small Angle Slot divertor magnetic topology]

The Small Angle Slot (SAS) was recently installed on DIII-D as an advanced divertor, promising easier plasma detachment and lower temperatures across the whole target. A twofold study of the SAS magnetic topology is presented in this paper. On one hand, a twodimensional uncertainty quantification analysis is carried out through a Monte Carlo approach in order to understand the level of accuracy of two-dimensional equilibrium computations in reconstructing the strike point and angle onto the divertor. Under typical experimental conditions, the uncertainties are found to be roughly 6.8 mm and 0.56 deg, respectively. On the other hand, a three-dimensional “vacuum” analysis is carried out to understand the effects of typical external perturbation fields on the scrape-off layer topology. When the threedimensional I-coils are switched on, poloidally-localized lobes are found to appear, grow, and hit the SAS target, although barely, even for 5 kA; at the same time, the strike point modulation is found to be roughly 1.8 mm and thus negligible for most purposes. Furthermore, such results complement previous two-dimensional analyses in characterizing typical SAS equilibria and provide useful background information for planning and interpreting SAS experiments.
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [2] ;  [4] ;  [2]
  1. Oak Ridge Associated Univ., Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Univ. of California-San Diego, San Diego, CA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
FC02-04ER54698; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 2; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
General Atomics, San Diego, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma physics; DIII-D; magnetic topology; divertor footprint
OSTI Identifier:
1415991
Alternate Identifier(s):
OSTI ID: 1422607

Trevisan, Gregorio L., Lao, Lang L., Evans, Todd E., Guo, Hou Yang, Orlov, Dmitry M., Strait, Edward J., Wingen, Andreas, and Wu, Wen. Effects of two-dimensional magnetic uncertainties and three-dimensional error and perturbation fields on the Small Angle Slot divertor geometry and topology [Effects of two- and three-dimensional magnetic fields on the Small Angle Slot divertor magnetic topology]. United States: N. p., Web. doi:10.1088/1741-4326/aa9dab.
Trevisan, Gregorio L., Lao, Lang L., Evans, Todd E., Guo, Hou Yang, Orlov, Dmitry M., Strait, Edward J., Wingen, Andreas, & Wu, Wen. Effects of two-dimensional magnetic uncertainties and three-dimensional error and perturbation fields on the Small Angle Slot divertor geometry and topology [Effects of two- and three-dimensional magnetic fields on the Small Angle Slot divertor magnetic topology]. United States. doi:10.1088/1741-4326/aa9dab.
Trevisan, Gregorio L., Lao, Lang L., Evans, Todd E., Guo, Hou Yang, Orlov, Dmitry M., Strait, Edward J., Wingen, Andreas, and Wu, Wen. 2018. "Effects of two-dimensional magnetic uncertainties and three-dimensional error and perturbation fields on the Small Angle Slot divertor geometry and topology [Effects of two- and three-dimensional magnetic fields on the Small Angle Slot divertor magnetic topology]". United States. doi:10.1088/1741-4326/aa9dab.
@article{osti_1415991,
title = {Effects of two-dimensional magnetic uncertainties and three-dimensional error and perturbation fields on the Small Angle Slot divertor geometry and topology [Effects of two- and three-dimensional magnetic fields on the Small Angle Slot divertor magnetic topology]},
author = {Trevisan, Gregorio L. and Lao, Lang L. and Evans, Todd E. and Guo, Hou Yang and Orlov, Dmitry M. and Strait, Edward J. and Wingen, Andreas and Wu, Wen},
abstractNote = {The Small Angle Slot (SAS) was recently installed on DIII-D as an advanced divertor, promising easier plasma detachment and lower temperatures across the whole target. A twofold study of the SAS magnetic topology is presented in this paper. On one hand, a twodimensional uncertainty quantification analysis is carried out through a Monte Carlo approach in order to understand the level of accuracy of two-dimensional equilibrium computations in reconstructing the strike point and angle onto the divertor. Under typical experimental conditions, the uncertainties are found to be roughly 6.8 mm and 0.56 deg, respectively. On the other hand, a three-dimensional “vacuum” analysis is carried out to understand the effects of typical external perturbation fields on the scrape-off layer topology. When the threedimensional I-coils are switched on, poloidally-localized lobes are found to appear, grow, and hit the SAS target, although barely, even for 5 kA; at the same time, the strike point modulation is found to be roughly 1.8 mm and thus negligible for most purposes. Furthermore, such results complement previous two-dimensional analyses in characterizing typical SAS equilibria and provide useful background information for planning and interpreting SAS experiments.},
doi = {10.1088/1741-4326/aa9dab},
journal = {Nuclear Fusion},
number = 2,
volume = 58,
place = {United States},
year = {2018},
month = {1}
}