Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

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.

doi:10.1063/1.5016160

Title: Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

Journal Article · Fri Apr 20 00:00:00 EDT 2018 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.5016160· OSTI ID:1435647

Austin, Max E. ^[1]; Bardoczi, Laszlo ^[2]; Collins, Cami S. ^[3];

^[3]; Davis, E. ^[4]; Du, X. ^[5]; Ferron, J. ^[3];

^[6]; Heidbrink, William W. ^[5]; Holcomb, Christopher T. ^[7]; McKee, G. R. ^[8];

^[3]; Petty, C. C. ^[3];

^[6];

^[3];

^[9];

^[2]; Van Zeeland, M. A. ^[3];

^[9] more »

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)

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, P_beam ≥ 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.

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Research Organization:: 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 Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FC02-04ER54698; AO52-07NA27344; AC02-09CH11466; FG02-94ER54235; FG02-08ER54999

OSTI ID:: 1435647

Alternate ID(s):: OSTI ID: 1434191; OSTI ID: 1497981; OSTI ID: 1648938

Report Number(s):: LLNL-JRNL-758950; TRN: US1900079

Journal Information:: Physics of Plasmas, Vol. 25, Issue 5; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 17 works

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References (47)

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The effect of plasma shape and neutral beam mix on the rotation threshold for RMP-ELM suppression Paz-Soldan, C.; Nazikian, R.; Cui, L. Nuclear Fusion, Vol. 59, Issue 5 https://doi.org/10.1088/1741-4326/ab04c0	journal	March 2019
Dependence of alpha-particle-driven Alfvén eigenmode linear stability on device magnetic field strength and consequences for next-generation tokamaks Tolman, E. A.; Loureiro, N. F.; Rodrigues, P. Nuclear Fusion, Vol. 59, Issue 4 https://doi.org/10.1088/1741-4326/ab058f	journal	March 2019
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Analysis of Alfven eigenmode destabilization in ITER using a Landau closure model Varela, J.; Spong, D. A.; Garcia, L. Nuclear Fusion, Vol. 59, Issue 7 https://doi.org/10.1088/1741-4326/ab1ebe	journal	June 2019
Subdominant modes and optimization trends of DIII-D reverse magnetic shear configurations Varela, J.; Spong, D. A.; Murakami, M. arXiv https://doi.org/10.48550/arxiv.1904.01193	text	January 2019
Analysis of Alfven Eigenmode destabilization in ITER using a Landau closure model Varela, J.; Spong, D. A.; Garcia, L. arXiv https://doi.org/10.48550/arxiv.1906.05700	text	January 2019

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