Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks
Abstract
Here, an engineering upgrade to the neutral beam system at the DIII-D tokamak enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic (E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, Pbeam ≥ 2MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.
- Authors:
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[3];
[6];
[3];
[6];
[3];
[3];
[9];
[2];
[9]
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- Univ. of Texas, Austin, TX (United States)
- Oak Ridge Associated Univ., Oak Ridge, TN (United States)
- General Atomics, San Diego, CA (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Univ. of California Irvine, Irvine, CA (United States)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Wisconsin-Madison, Madison, WI (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Research Org.:
- General Atomics, San Diego, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1435647
- Alternate Identifier(s):
- OSTI ID: 1434191; OSTI ID: 1497981; OSTI ID: 1648938
- Report Number(s):
- LLNL-JRNL-758950
Journal ID: ISSN 1070-664X; TRN: US1900079
- Grant/Contract Number:
- FC02-04ER54698; AO52-07NA27344; AC02-09CH11466; FG02-94ER54235; FG02-08ER54999
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physics of Plasmas
- Additional Journal Information:
- Journal Volume: 25; Journal Issue: 5; Journal ID: ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Physics - Plasma physics
Citation Formats
Austin, Max E., Bardoczi, Laszlo, Collins, Cami S., Crowley, B., Davis, E., Du, X., Ferron, J., Grierson, Brian A., Heidbrink, William W., Holcomb, Christopher T., McKee, G. R., Pawley, C., Petty, C. C., Podesta, M., Rauch, J., Scoville, J. T., Spong, D. A., Thome, K. E., Van Zeeland, M. A., Varela, J., Victor, B., and Pace, D. C. Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks. United States: N. p., 2018.
Web. doi:10.1063/1.5016160.
Austin, Max E., Bardoczi, Laszlo, Collins, Cami S., Crowley, B., Davis, E., Du, X., Ferron, J., Grierson, Brian A., Heidbrink, William W., Holcomb, Christopher T., McKee, G. R., Pawley, C., Petty, C. C., Podesta, M., Rauch, J., Scoville, J. T., Spong, D. A., Thome, K. E., Van Zeeland, M. A., Varela, J., Victor, B., & Pace, D. C. Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks. United States. https://doi.org/10.1063/1.5016160
Austin, Max E., Bardoczi, Laszlo, Collins, Cami S., Crowley, B., Davis, E., Du, X., Ferron, J., Grierson, Brian A., Heidbrink, William W., Holcomb, Christopher T., McKee, G. R., Pawley, C., Petty, C. C., Podesta, M., Rauch, J., Scoville, J. T., Spong, D. A., Thome, K. E., Van Zeeland, M. A., Varela, J., Victor, B., and Pace, D. C. Fri .
"Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks". United States. https://doi.org/10.1063/1.5016160. https://www.osti.gov/servlets/purl/1435647.
@article{osti_1435647,
title = {Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks},
author = {Austin, Max E. and Bardoczi, Laszlo and Collins, Cami S. and Crowley, B. and Davis, E. and Du, X. and Ferron, J. and Grierson, Brian A. and Heidbrink, William W. and Holcomb, Christopher T. and McKee, G. R. and Pawley, C. and Petty, C. C. and Podesta, M. and Rauch, J. and Scoville, J. T. and Spong, D. A. and Thome, K. E. and Van Zeeland, M. A. and Varela, J. and Victor, B. and Pace, D. C.},
abstractNote = {Here, an engineering upgrade to the neutral beam system at the DIII-D tokamak enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic (E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, Pbeam ≥ 2MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.},
doi = {10.1063/1.5016160},
journal = {Physics of Plasmas},
number = 5,
volume = 25,
place = {United States},
year = {Fri Apr 20 00:00:00 EDT 2018},
month = {Fri Apr 20 00:00:00 EDT 2018}
}
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Works referencing / citing this record:
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