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Hybrid simulation of NBI fast-ion losses due to the Alfvén eigenmode bursts in the Large Helical Device and the comparison with the fast-ion loss detector measurements

Part of: Focus on Fusion

Published online by Cambridge University Press:  03 November 2020

R. Seki Open the ORCID record for R. Seki [Opens in a new window] ,
Y. Todo Open the ORCID record for Y. Todo [Opens in a new window] ,
Y. Suzuki Open the ORCID record for Y. Suzuki [Opens in a new window] ,
K. Ogawa Open the ORCID record for K. Ogawa [Opens in a new window] ,
M. Isobe Open the ORCID record for M. Isobe [Opens in a new window] ,
D. A. Spong Open the ORCID record for D. A. Spong [Opens in a new window]  and
M. Osakabe Open the ORCID record for M. Osakabe [Opens in a new window]
R. Seki*
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan The Graduate University for Advanced Studies, SOKENDAI, Toki, Japan
Y. Todo
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan
Y. Suzuki
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan The Graduate University for Advanced Studies, SOKENDAI, Toki, Japan
K. Ogawa
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan The Graduate University for Advanced Studies, SOKENDAI, Toki, Japan
M. Isobe
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan The Graduate University for Advanced Studies, SOKENDAI, Toki, Japan
D. A. Spong
Affiliation:
Oak Ridge National Laboratory, Oak Ridge, USA
M. Osakabe
Affiliation:
National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, Japan The Graduate University for Advanced Studies, SOKENDAI, Toki, Japan
*
†Email address for correspondence: [email protected]
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Abstract

The multiphase simulations are conducted with the kinetic-magnetohydrodynamics hybrid code MEGA to investigate the spatial and the velocity distributions of lost fast ions due to the Alfvén eigenmode (AE) bursts in the Large Helical Device plasmas. It is found that fast ions are lost along the divertor region with helical symmetry both before and during the AE burst except for the promptly lost particles. On the other hand, several peaks are present in the spatial distribution of lost fast ions along the divertor region. These peaks along the divertor region can be attributed to the deviation of the fast-ion orbits from the magnetic surfaces due to the grad-B and the curvature drifts. For comparison with the velocity distribution of lost fast ions measured by the fast-ion loss detector (FILD), the ‘numerical FILD’ which solves the Newton–Lorentz equation is constructed in the MEGA code. The velocity distribution of lost fast ions detected by the numerical FILD during AE burst is in good qualitative agreement with the experimental FILD measurements. During the AE burst, fast ions with high energy (100–180 keV) are detected by the numerical FILD, while co-going fast ions lost to the divertor region are the particles with energy lower than 50 keV.

Keywords

fusion plasmaplasma simulation
Type
Research Article
Information
Journal of Plasma Physics , Volume 86 , Issue 5 , October 2020 , 905860520
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Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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References

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