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Title: The phase-space dependence of fast-ion interaction with tearing modes

Abstract

Modulation of various neutral beam sources probes the interaction of fast ions with tearing modes (TM) in the DIII-D tokamak. As measured by electron cyclotron emission, the (m,n) = (2,1) tearing modes have an island width of ~8 cm and change phase 180 at the q = 2 surface. (Here, m is the poloidal mode number and n is the toroidal mode number.) Deuterium neutral beam injection by six sources with differing injection geometries produces the fast ions. To study the interaction in different parts of phase space, on successive discharges, one of the six sources is modulated at 20 Hz to populate different fast-ion orbits. The modulation only changes the island width by a few millimeters, implying that any fast-ion effect on mode stability is below detection limits. When compared to the expected signals in the absence of TM-induced transport, both the average and modulated neutron signals deviate, implying that fast-ion transport occurs in much of phase space. Fast-ion D-α (FIDA) measurements detect reductions in signal at wavelengths that are sensitive to counter-passing ions. Neutral particle analyzer data imply poor confinement of trapped fast ions. Lastly, calculations of the expected fast-ion transport that use measured TM properties successfully reproducemore » the data.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [3]; ORCiD logo [7];  [1];  [8];  [1]
  1. Univ. of California, Irvine, CA (United States). Department of Physics and Astronomy
  2. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  3. General Atomics, San Diego, CA (United States)
  4. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  5. General Atomics, San Diego, CA (United States). Inertial Fusion Technology
  6. Univ. of California, Irvine, CA (United States)
  7. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States). NSTX
  8. General Atomics, San Diego, CA, United States of America
Publication Date:
Research Org.:
Dept. of Energy (DOE), Washington DC (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1429876
Report Number(s):
DOE-GA-54698
Journal ID: ISSN 0029-5515; TRN: US1802485
Grant/Contract Number:  
FC02-04ER54698
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 8; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tearing modes; fast ions; FIDA

Citation Formats

Heidbrink, William W., Bardoczi, Laszlo, Collins, Cami S., Kramer, Gerrit J., La Haye, Robert J., Lin, D. J., Muscatello, Christopher M., Podesta, Mario, Stagner, Luke, Van Zeeland, Michael A., and Zhu, Yubao. The phase-space dependence of fast-ion interaction with tearing modes. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aab7b6.
Heidbrink, William W., Bardoczi, Laszlo, Collins, Cami S., Kramer, Gerrit J., La Haye, Robert J., Lin, D. J., Muscatello, Christopher M., Podesta, Mario, Stagner, Luke, Van Zeeland, Michael A., & Zhu, Yubao. The phase-space dependence of fast-ion interaction with tearing modes. United States. doi:10.1088/1741-4326/aab7b6.
Heidbrink, William W., Bardoczi, Laszlo, Collins, Cami S., Kramer, Gerrit J., La Haye, Robert J., Lin, D. J., Muscatello, Christopher M., Podesta, Mario, Stagner, Luke, Van Zeeland, Michael A., and Zhu, Yubao. Tue . "The phase-space dependence of fast-ion interaction with tearing modes". United States. doi:10.1088/1741-4326/aab7b6. https://www.osti.gov/servlets/purl/1429876.
@article{osti_1429876,
title = {The phase-space dependence of fast-ion interaction with tearing modes},
author = {Heidbrink, William W. and Bardoczi, Laszlo and Collins, Cami S. and Kramer, Gerrit J. and La Haye, Robert J. and Lin, D. J. and Muscatello, Christopher M. and Podesta, Mario and Stagner, Luke and Van Zeeland, Michael A. and Zhu, Yubao},
abstractNote = {Modulation of various neutral beam sources probes the interaction of fast ions with tearing modes (TM) in the DIII-D tokamak. As measured by electron cyclotron emission, the (m,n) = (2,1) tearing modes have an island width of ~8 cm and change phase 180 at the q = 2 surface. (Here, m is the poloidal mode number and n is the toroidal mode number.) Deuterium neutral beam injection by six sources with differing injection geometries produces the fast ions. To study the interaction in different parts of phase space, on successive discharges, one of the six sources is modulated at 20 Hz to populate different fast-ion orbits. The modulation only changes the island width by a few millimeters, implying that any fast-ion effect on mode stability is below detection limits. When compared to the expected signals in the absence of TM-induced transport, both the average and modulated neutron signals deviate, implying that fast-ion transport occurs in much of phase space. Fast-ion D-α (FIDA) measurements detect reductions in signal at wavelengths that are sensitive to counter-passing ions. Neutral particle analyzer data imply poor confinement of trapped fast ions. Lastly, calculations of the expected fast-ion transport that use measured TM properties successfully reproduce the data.},
doi = {10.1088/1741-4326/aab7b6},
journal = {Nuclear Fusion},
number = 8,
volume = 58,
place = {United States},
year = {2018},
month = {7}
}

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