1
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Wang L, Wang HQ, Ding S, Garofalo AM, Gong XZ, Eldon D, Guo HY, Leonard AW, Hyatt AW, Qian JP, Weisberg DB, McClenaghan J, Fenstermacher ME, Lasnier CJ, Watkins JG, Shafer MW, Xu GS, Huang J, Ren QL, Buttery RJ, Humphreys DA, Thomas DM, Zhang B, Liu JB. Integration of full divertor detachment with improved core confinement for tokamak fusion plasmas. Nat Commun 2021; 12:1365. [PMID: 33649306 PMCID: PMC7921092 DOI: 10.1038/s41467-021-21645-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/29/2021] [Indexed: 11/24/2022] Open
Abstract
Divertor detachment offers a promising solution to the challenge of plasma-wall interactions for steady-state operation of fusion reactors. Here, we demonstrate the excellent compatibility of actively controlled full divertor detachment with a high-performance (βN ~ 3, H98 ~ 1.5) core plasma, using high-βp (poloidal beta, βp > 2) scenario characterized by a sustained core internal transport barrier (ITB) and a modest edge transport barrier (ETB) in DIII-D tokamak. The high-βp high-confinement scenario facilitates divertor detachment which, in turn, promotes the development of an even stronger ITB at large radius with a weaker ETB. This self-organized synergy between ITB and ETB, leads to a net gain in energy confinement, in contrast to the net confinement loss caused by divertor detachment in standard H-modes. These results show the potential of integrating excellent core plasma performance with an efficient divertor solution, an essential step towards steady-state operation of reactor-grade plasmas.
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Affiliation(s)
- L Wang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - H Q Wang
- General Atomics, San Diego, CA, USA.
| | - S Ding
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
- Oak Ridge Associated Universities, Oak Ridge, TN, USA
| | | | - X Z Gong
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - D Eldon
- General Atomics, San Diego, CA, USA
| | - H Y Guo
- General Atomics, San Diego, CA, USA
| | | | | | - J P Qian
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | | | | | - C J Lasnier
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - J G Watkins
- Sandia National Laboratories, Livermore, CA, USA
| | - M W Shafer
- Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - G S Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J Huang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - Q L Ren
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | | | | | - B Zhang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J B Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
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2
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Meyer WH, Allen SL, Samuell CM, Fenstermacher ME. Tomographic analysis of tangential viewing cameras (invited). Rev Sci Instrum 2018; 89:10K110. [PMID: 30399959 DOI: 10.1063/1.5038586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 06/19/2018] [Indexed: 06/08/2023]
Abstract
Many tokamaks now use visible light cameras to observe plasma-wall interactions and integrated line emission. The DIII-D coherence imaging spectroscopy diagnostic cameras image interferograms that encode line integrated velocity. By modeling the 2D camera image pixels as line of sight integrals through an axisymmetric discrete grid, it is possible to do tomographic analysis to determine the local plasma line emissivity and parallel velocity. Methods to solve the inverse problem posed by these tangential viewing cameras are presented. The inversion begins with calculation of the sparse response matrix that encompasses all the geometry and diagnostic information and reduces the process of image formation to a sparse matrix-vector multiply. This work includes techniques for determining the detailed geometry of the camera views and methods for handling physical quantities that vary spatially. Additionally, the size of the response matrix has driven the development of capability to distribute the coarse parallel calculation across a heterogeneous cluster of computers on the Energy Sciences Network. Iterative techniques are then used to solve the sparse matrix-vector linear system.
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Affiliation(s)
- W H Meyer
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S L Allen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C M Samuell
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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3
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Moyer RA, Bykov I, Orlov DM, Evans TE, Lee JS, Teklu AM, Fenstermacher ME, Makowski M, Lasnier CJ, Wang HQ, Watkins JG, Wu W. Imaging divertor strike point splitting in RMP ELM suppression experiments in the DIII-D tokamak. Rev Sci Instrum 2018; 89:10E106. [PMID: 30399795 DOI: 10.1063/1.5038350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 06/08/2018] [Indexed: 06/08/2023]
Abstract
Fast visible imaging of the lower divertor from above is used to study the structure and dynamics of lobes induced by resonant magnetic perturbations (RMPs) in Edge-Localized Mode (ELM) suppression experiments in DIII-D. The best compromise between the amount of light and sharp imaging was obtained using emission at 601 nm from Fulcher band molecular deuterium. Multiple spatially resolved peaks in the D2 emission, taken as a proxy for the particle flux, are readily resolved during RMPs, in contrast to the heat flux measured by infrared cameras, which shows little spatial structure in ITER-like conditions. The 25 mm objective lens provides high spatial resolution (2-4 mm/pixel) from the centerpost to the outer shelf over 40° toroidally that overlaps the field of view of the IRTV that measures the divertor heat flux, allowing direct comparison in non-axisymmetric discharges. The image is coupled to a Phantom 7.3 camera using a Schott wound fiber bundle, providing high temporal resolution that allows the lobe dynamics to be resolved between ELMs and across ELM suppression onset. These measurements are used to study the heat and particle flux in 3D magnetic fields and to validate models for the plasma response to RMPs.
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Affiliation(s)
- R A Moyer
- Center for Energy Research, University of California San Diego, La Jolla, California 92093-0417, USA
| | - I Bykov
- Center for Energy Research, University of California San Diego, La Jolla, California 92093-0417, USA
| | - D M Orlov
- Center for Energy Research, University of California San Diego, La Jolla, California 92093-0417, USA
| | - T E Evans
- General Atomics, San Diego, California 92186-5608, USA
| | - J S Lee
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - A M Teklu
- Oregon State University, Corvallis, Oregon 97331, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M Makowski
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C J Lasnier
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - H Q Wang
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA
| | - J G Watkins
- Sandia National Laboratories, California, Livermore, California 94551-0969, USA
| | - W Wu
- General Atomics, San Diego, California 92186-5608, USA
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4
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Jaervinen AE, Allen SL, Eldon D, Fenstermacher ME, Groth M, Hill DN, Leonard AW, McLean AG, Porter GD, Rognlien TD, Samuell CM, Wang HQ. E×B Flux Driven Detachment Bifurcation in the DIII-D Tokamak. Phys Rev Lett 2018; 121:075001. [PMID: 30169054 DOI: 10.1103/physrevlett.121.075001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 06/21/2018] [Indexed: 06/08/2023]
Abstract
A bifurcative step transition from low-density, high-temperature, attached divertor conditions to high-density, low-temperature, detached divertor conditions is experimentally observed in DIII-D tokamak plasmas as density is increased. The step transition is only observed in the high confinement mode and only when the B×∇B drift is directed towards the divertor. This work reports for the first time a theoretical explanation and numerical simulations that qualitatively reproduce this bifurcation and its dependence on the toroidal field direction. According to the model, the bifurcation is primarily driven by the interdependence of the E×B-drift fluxes, divertor electric potential structure, and divertor conditions. In the attached conditions, strong potential gradients in the low field side (LFS) divertor drive E×B-drift flux towards the high field side divertor, reinforcing low density, high temperature conditions in the LFS divertor leg. At the onset of detachment, reduction in the potential gradients in the LFS divertor leg reduce the E×B-drift flux as well, such that the divertor plasma evolves nonlinearly to high density, strongly detached conditions. Experimental estimates of the E×B-drift fluxes, based on divertor Thomson scattering measurements, and their dependence on the divertor conditions are qualitatively consistent with the numerical predictions. The implications for divertor power exhaust and detachment control in the next step fusion devices are discussed.
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Affiliation(s)
- A E Jaervinen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S L Allen
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D Eldon
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - M Groth
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D N Hill
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A W Leonard
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A G McLean
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G D Porter
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - T D Rognlien
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C M Samuell
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - H Q Wang
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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5
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Mioduszewski PK, Owen LW, Spong DA, Fenstermacher ME, Koniges AE, Rognlien TD, Umansky MV, Grossman A, Kugel HW. Power and Particle Handling and Wall Conditioning in NCSX. Fusion Science and Technology 2017. [DOI: 10.13182/fst07-a1302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- P. K. Mioduszewski
- Oak Ridge National Laboratory, P.O. Box 4008, Oak Ridge, Tennessee 37831-6169
| | - L. W. Owen
- Oak Ridge National Laboratory, P.O. Box 4008, Oak Ridge, Tennessee 37831-6169
| | - D. A. Spong
- Oak Ridge National Laboratory, P.O. Box 4008, Oak Ridge, Tennessee 37831-6169
| | - M. E. Fenstermacher
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551
| | - A. E. Koniges
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551
| | - T. D. Rognlien
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551
| | - M. V. Umansky
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551
| | - A. Grossman
- University of California at San Diego, Mail Code 0417, 9500 Gilman Drive La Jolla, California 92093-0417
| | - H. W. Kugel
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08544
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6
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Boivin RL, Luxon JL, Austin ME, Brooks NH, Burrell KH, Doyle EJ, Fenstermacher ME, Gray DS, Groth M, Hsieh CL, Jayakumar RJ, Lasnier CJ, Leonard AW, McKee GR, Moyer RA, Rhodes TL, Rost JC, Rudakov DL, Schaffer MJ, Strait EJ, Thomas DM, Van Zeeland M, Watkins JG, Watson GW, Wong CPC. DIII-D Diagnostic Systems. Fusion Science and Technology 2017. [DOI: 10.13182/fst05-a1043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - M. E. Austin
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of Texas–Austin, Austin, Texas
| | | | | | - E. J. Doyle
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–Los Angeles, Los Angeles, California
| | - M. E. Fenstermacher
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Lawrence Livermore National Laboratory, Livermore, California/University of California–Los Angeles, Los Angeles, California
| | - D. S. Gray
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–San Diego, La Jolla, California
| | - M. Groth
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Lawrence Livermore National Laboratory, Livermore, California/University of California–Los Angeles, Los Angeles, California
| | | | - R. J. Jayakumar
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Lawrence Livermore National Laboratory, Livermore, California/University of California–Los Angeles, Los Angeles, California
| | - C. J. Lasnier
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Lawrence Livermore National Laboratory, Livermore, California/University of California–Los Angeles, Los Angeles, California
| | | | - G. R. McKee
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of Wisconsin–Madison, Madison, Wisconsin
| | - R. A. Moyer
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–San Diego, La Jolla, California
| | - T. L. Rhodes
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–Los Angeles, Los Angeles, California
| | - J. C. Rost
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - D. L. Rudakov
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–San Diego, La Jolla, California
| | | | | | | | - M. Van Zeeland
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of Wisconsin–Madison, Madison, Wisconsin
| | - J. G. Watkins
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- Sandia National Laboratories, Albuquerque, New Mexico
| | - G. W. Watson
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
- University of California–Irvine, Irvine, California
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7
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Groebner RJ, Osborne TH, Fenstermacher ME, Leonard AW, Mahdavi MA, Moyer RA, Owen LW, Porter GD, Snyder PB, Stangeby PC, Rhodes TL, Wolf NS. Pedestal Studies in DIII-D. Fusion Science and Technology 2017. [DOI: 10.13182/fst05-a1056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. J. Groebner
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - T. H. Osborne
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | | | - A. W. Leonard
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - M. A. Mahdavi
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. A. Moyer
- University of California, San Diego, California
| | - L. W. Owen
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - G. D. Porter
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California
| | - P. B. Snyder
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | | | - T. L. Rhodes
- University of California, Los Angeles, California
| | - N. S. Wolf
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California
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8
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Mahdavi MA, Allen SL, Fenstermacher ME, Maingi R, Schaffer MJ, Stambaugh RD, Wade MR. Divertor Physics and Concept Development on DIII-D and Doublet-III Tokamaks. Fusion Science and Technology 2017. [DOI: 10.13182/fst05-a1061] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- M. A. Mahdavi
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
| | - S. L. Allen
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
| | | | - R. Maingi
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
| | - M. J. Schaffer
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
| | - R. D. Stambaugh
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
| | - M. R. Wade
- General Atomics, P.O. Box 85608 San Diego, California 92186-5608
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9
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Lasnier CJ, Allen SL, Ellis RE, Fenstermacher ME, McLean AG, Meyer WH, Morris K, Seppala LG, Crabtree K, Van Zeeland MA. Wide-angle ITER-prototype tangential infrared and visible viewing system for DIII-D. Rev Sci Instrum 2014; 85:11D855. [PMID: 25430268 DOI: 10.1063/1.4892897] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An imaging system with a wide-angle tangential view of the full poloidal cross-section of the tokamak in simultaneous infrared and visible light has been installed on DIII-D. The optical train includes three polished stainless steel mirrors in vacuum, which view the tokamak through an aperture in the first mirror, similar to the design concept proposed for ITER. A dichroic beam splitter outside the vacuum separates visible and infrared (IR) light. Spatial calibration is accomplished by warping a CAD-rendered image to align with landmarks in a data image. The IR camera provides scrape-off layer heat flux profile deposition features in diverted and inner-wall-limited plasmas, such as heat flux reduction in pumped radiative divertor shots. Demonstration of the system to date includes observation of fast-ion losses to the outer wall during neutral beam injection, and shows reduced peak wall heat loading with disruption mitigation by injection of a massive gas puff.
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Affiliation(s)
- C J Lasnier
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - S L Allen
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - R E Ellis
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - A G McLean
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - W H Meyer
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - K Morris
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - L G Seppala
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA
| | - K Crabtree
- College of Optics, University of Arizona, Tucson, Arizona 85721, USA
| | - M A Van Zeeland
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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10
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Solomon WM, Snyder PB, Burrell KH, Fenstermacher ME, Garofalo AM, Grierson BA, Loarte A, McKee GR, Nazikian R, Osborne TH. Access to a new plasma edge state with high density and pressures using the quiescent H mode. Phys Rev Lett 2014; 113:135001. [PMID: 25302895 DOI: 10.1103/physrevlett.113.135001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Indexed: 06/04/2023]
Abstract
A path to a new high performance regime has been discovered in tokamaks that could improve the attractiveness of a fusion reactor. Experiments on DIII-D using a quiescent H-mode edge have navigated a valley of improved edge peeling-ballooning stability that opens up with strong plasma shaping at high density, leading to a doubling of the edge pressure over the standard H mode with edge localized modes at these parameters. The thermal energy confinement time increases as a result of both the increased pedestal height and improvements in the core transport and reduced low-k turbulence. Calculations of the pedestal height and width as a function of density using constraints imposed by peeling-ballooning and kinetic-ballooning theory are in quantitative agreement with the measurements.
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Affiliation(s)
- W M Solomon
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - P B Snyder
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - K H Burrell
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - B A Grierson
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - A Loarte
- ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 Saint Paul Lez Durance Cedex, France
| | - G R McKee
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - R Nazikian
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - T H Osborne
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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11
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Baylor LR, Commaux N, Jernigan TC, Brooks NH, Combs SK, Evans TE, Fenstermacher ME, Isler RC, Lasnier CJ, Meitner SJ, Moyer RA, Osborne TH, Parks PB, Snyder PB, Strait EJ, Unterberg EA, Loarte A. Reduction of edge-localized mode intensity using high-repetition-rate pellet injection in tokamak H-mode plasmas. Phys Rev Lett 2013; 110:245001. [PMID: 25165932 DOI: 10.1103/physrevlett.110.245001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Indexed: 06/03/2023]
Abstract
High repetition rate injection of deuterium pellets from the low-field side (LFS) of the DIII-D tokamak is shown to trigger high-frequency edge-localized modes (ELMs) at up to 12× the low natural ELM frequency in H-mode deuterium plasmas designed to match the ITER baseline configuration in shape, normalized beta, and input power just above the H-mode threshold. The pellet size, velocity, and injection location were chosen to limit penetration to the outer 10% of the plasma. The resulting perturbations to the plasma density and energy confinement time are thus minimal (<10%). The triggered ELMs occur at much lower normalized pedestal pressure than the natural ELMs, suggesting that the pellet injection excites a localized high-n instability. Triggered ELMs produce up to 12× lower energy and particle fluxes to the divertor, and result in a strong decrease in plasma core impurity density. These results show for the first time that shallow, LFS pellet injection can dramatically accelerate the ELM cycle and reduce ELM energy fluxes on plasma facing components, and is a viable technique for real-time control of ELMs in ITER.
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Affiliation(s)
- L R Baylor
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - N Commaux
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - T C Jernigan
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - N H Brooks
- General Atomics, San Diego, California 92186-5608, USA
| | - S K Combs
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - T E Evans
- General Atomics, San Diego, California 92186-5608, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - R C Isler
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - C J Lasnier
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S J Meitner
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - R A Moyer
- University of California San Diego, La Jolla, California 92093-0319, USA
| | - T H Osborne
- General Atomics, San Diego, California 92186-5608, USA
| | - P B Parks
- General Atomics, San Diego, California 92186-5608, USA
| | - P B Snyder
- General Atomics, San Diego, California 92186-5608, USA
| | - E J Strait
- General Atomics, San Diego, California 92186-5608, USA
| | - E A Unterberg
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8072, USA
| | - A Loarte
- ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance Cedex, France
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12
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Lanctot MJ, Holcomb CT, Allen SL, Fenstermacher ME, Luce TC. Pedestal magnetic field measurements using a motional Stark effect polarimeter. Rev Sci Instrum 2012; 83:10E319. [PMID: 23126977 DOI: 10.1063/1.4733342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Temperature-controlled, 0.15 nm interference filters were installed on an edge-viewing system of the motional Stark effect (MSE) polarimeter on the DIII-D tokamak. The upgraded system provides a factor of two reduction in the bandpass compared to the previous design, and linear control of the bandpass, which is unaltered by wavelength tuning. With the new system, there is a reduced dependence of the inferred polarization angle on the filter wavelength calibration. Recent measurements from the calibrated edge-viewing system show increased agreement with other MSE arrays.
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Affiliation(s)
- M J Lanctot
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
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13
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Howard J, Diallo A, Creese M, Blackwell BD, Allen SL, Ellis RM, Porter GD, Meyer W, Fenstermacher ME, Brooks NH, Van Zeeland ME, Boivin RL. Doppler coherence imaging and tomography of flows in tokamak plasmas (invited). Rev Sci Instrum 2010; 81:10E528. [PMID: 21034056 DOI: 10.1063/1.3492422] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This article describes the results of spatial heterodyne Doppler "coherence imaging" of carbon ion flows in the divertor region of the DIII-D tokamak. Spatially encoded interferometric projections of doubly ionized carbon emission at 465 nm have been demodulated and tomographically inverted to obtain the spatial distribution of the carbon ion parallel flow and emissivity. The operating principles of the new instruments are described, and the link between measured properties and line integrals of the flow field are established. An iterative simultaneous arithmetic reconstruction procedure is applied to invert the interferometric phase shift projections, and the reconstructed parallel flow field amplitudes are found to be in reasonable agreement with UEDGE modeling.
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Affiliation(s)
- J Howard
- Plasma Research Laboratory, The Australian National University, Canberra 0200, Australia.
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14
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Schmitz O, Evans TE, Fenstermacher ME, Unterberg EA, Austin ME, Bray BD, Brooks NH, Frerichs H, Groth M, Jakubowski MW, Lasnier CJ, Lehnen M, Leonard AW, Mordijck S, Moyer RA, Osborne TH, Reiter D, Samm U, Schaffer MJ, Unterberg B, West WP. Resonant pedestal pressure reduction induced by a thermal transport enhancement due to stochastic magnetic boundary layers in high temperature plasmas. Phys Rev Lett 2009; 103:165005. [PMID: 19905705 DOI: 10.1103/physrevlett.103.165005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Indexed: 05/28/2023]
Abstract
Good alignment of the magnetic field line pitch angle with the mode structure of an external resonant magnetic perturbation (RMP) field is shown to induce modulation of the pedestal electron pressure p(e) in high confinement high rotation plasmas at the DIII-D tokamak with a shape similar to ITER, the next step tokamak experiment. This is caused by an edge safety factor q95 resonant enhancement of the thermal transport, while in contrast, the RMP induced particle pump out does not show a significant resonance. The measured p(e) reduction correlates to an increase in the modeled stochastic layer width during pitch angle variations matching results from resistive low rotation plasmas at the TEXTOR tokamak. These findings suggest a field line pitch angle resonant formation of a stochastic magnetic edge layer as an explanation for the q95 resonant character of type-I edge localized mode suppression by RMPs.
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Affiliation(s)
- O Schmitz
- Forschungszentrum Jülich GmbH, IEF4-Plasma Physics, 52428 Jülich, Germany
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15
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Burrell KH, Osborne TH, Snyder PB, West WP, Fenstermacher ME, Groebner RJ, Gohil P, Leonard AW, Solomon WM. Quiescent H-mode plasmas with strong edge rotation in the cocurrent direction. Phys Rev Lett 2009; 102:155003. [PMID: 19518641 DOI: 10.1103/physrevlett.102.155003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Indexed: 05/27/2023]
Abstract
For the first time in any tokamak, quiescent H-mode (QH-mode) plasmas have been created with strong edge rotation in the direction of the plasma current. This confirms the theoretical prediction that the QH mode should exist with either sign of the edge rotation provided the magnitude of the shear in the edge rotation is sufficiently large and demonstrates that counterinjection and counteredge rotation are not essential for the QH mode. Accordingly, the present work demonstrates a substantial broadening of the QH-mode operating space and represents a significant confirmation of the theory.
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Affiliation(s)
- K H Burrell
- General Atomics, San Diego, California 92186-5608, USA
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16
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Groth M, Ellis RM, Brooks NH, Fenstermacher ME, Lasnier CJ, Meyer WH, Moeller JM. Measurements of spatial line emission profiles in the main scrape-off layer of the DIII-D tokamak. Rev Sci Instrum 2009; 80:033505. [PMID: 19334920 DOI: 10.1063/1.3103575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A video camera system is described as that measures the spatial distribution of visible line emission emitted from the main scrape-off layer (SOL) of plasmas in the DIII-D tokamak. A wide-angle lens installed on an equatorial port and an in-vessel mirror, which intercepts part of the lens' view, provide simultaneous tangential views of the SOL on the low-field and high-field sides of the plasma's equatorial plane. Tomographic reconstruction techniques are used to calculate the two-dimensional (2D) poloidal profiles from the raw data, and one-dimensional (1D) poloidal profiles simulating chordal views of other optical diagnostics from the 2D profiles. The 2D profiles can be compared with SOL plasma simulations; the 1D profiles with measurements from spectroscopic diagnostics. Sample results are presented, which elucidate carbon transport in plasmas with toroidally uniform injection of methane and argon transport in disruption mitigation experiments with massive gas jet injection.
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Affiliation(s)
- M Groth
- Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California, 94551-0808, USA
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17
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Rudakov DL, Yu JH, Boedo JA, Hollmann EM, Krasheninnikov SI, Moyer RA, Muller SH, Pigarov AY, Rosenberg M, Smirnov RD, West WP, Boivin RL, Bray BD, Brooks NH, Hyatt AW, Wong CPC, Roquemore AL, Skinner CH, Solomon WM, Ratynskaia S, Fenstermacher ME, Groth M, Lasnier CJ, McLean AG, Stangeby PC. Dust measurements in tokamaks (invited). Rev Sci Instrum 2008; 79:10F303. [PMID: 19044616 DOI: 10.1063/1.2969422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Dust production and accumulation present potential safety and operational issues for the ITER. Dust diagnostics can be divided into two groups: diagnostics of dust on surfaces and diagnostics of dust in plasma. Diagnostics from both groups are employed in contemporary tokamaks; new diagnostics suitable for ITER are also being developed and tested. Dust accumulation in ITER is likely to occur in hidden areas, e.g., between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In the DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering is able to resolve particles between 0.16 and 1.6 microm in diameter; using these data the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in two-dimension with a single camera or three-dimension using multiple cameras, but determination of particle size is challenging. In order to calibrate diagnostics and benchmark dust dynamics modeling, precharacterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase in carbon line (CI, CII, C(2) dimer) and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.
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Affiliation(s)
- D L Rudakov
- University of California, San Diego, California 92093, USA
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18
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Evans TE, Roeder RKW, Carter JA, Rapoport BI, Fenstermacher ME, Lasnier CJ. Experimental signatures of homoclinic tangles in poloidally diverted tokamaks. ACTA ACUST UNITED AC 2005. [DOI: 10.1088/1742-6596/7/1/015] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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19
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Evans TE, Moyer RA, Thomas PR, Watkins JG, Osborne TH, Boedo JA, Doyle EJ, Fenstermacher ME, Finken KH, Groebner RJ, Groth M, Harris JH, La Haye RJ, Lasnier CJ, Masuzaki S, Ohyabu N, Pretty DG, Rhodes TL, Reimerdes H, Rudakov DL, Schaffer MJ, Wang G, Zeng L. Suppression of large edge-localized modes in high-confinement DIII-D plasmas with a stochastic magnetic boundary. Phys Rev Lett 2004; 92:235003. [PMID: 15245164 DOI: 10.1103/physrevlett.92.235003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2003] [Indexed: 05/24/2023]
Abstract
A stochastic magnetic boundary, produced by an applied edge resonant magnetic perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H mode transport barrier and core confinement are unaffected by the stochastic boundary, despite a threefold drop in the toroidal rotation. These results demonstrate that stochastic boundaries are compatible with H modes and may be attractive for ELM control in next-step fusion tokamaks.
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Affiliation(s)
- T E Evans
- General Atomics, San Diego, California, USA
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20
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Allen SL, Brown MD, Byers JA, Casper TA, Cohen BI, Cohen RH, Fenstermacher ME, Foote JH, Hooper EB, Lasnier CJ, Lopez P, Makowski MA, Marinak MM, Meyer WH, Moller JM, Nevins WM, Rice BW, Rognlien TD, Smith GR, Stallard BW, Scharlemann ET, Thomassen KI, Wood RD, Hoshino K, Oasa K, Oda T, Odajima K, Ogawa T, Ohgo T. Nonlinear absorption of high power free-electron-laser-generated microwaves at electron cyclotron resonance heating frequencies in the MTX tokamak. Phys Rev Lett 1994; 72:1348-1351. [PMID: 10056690 DOI: 10.1103/physrevlett.72.1348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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21
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Schmidt JA, Thomassen KI, Goldston RJ, Neilson GH, Nevins WM, Sinnis JC, Andersen P, Bair W, Barr WL, Batchelor DB, Baxi C, Berg G, Bernabei S, Bialek JM, Bonoli PT, Boozer A, Bowers D, Bronner G, Brooks JN, Brown TG, Bulmer R, Butner D, Campbell R, Casper T, Chaniotakis E, Chaplin M, Chen SJ, Chin E, Chrzanowski J, Citrolo J, Cole MJ, Dahlgren F, Davis FC, Davis J, Davis S, Diatchenko N, Dinkevich S, Feldshteyn Y, Felker B, Feng T, Fenstermacher ME, Fleming R, Fogarty PJ, Fragetta W, Fredd E, Gabler M, Galambos J, Gohar Y, Goranson PL, Greenough N, Grisham LR, Haines J, Haney S, Hassenzahl W, Heim J, Heitzenroeder PJ, Hill DN, Hodapp T, Houlberg WA, Hubbard A, Hyatt A, Jackson M, Jaeger EF, Jardin SC, Johnson J, Jones GH, Juliano DR, Junge R, Kalish M, Kessel CE, Knutson D, LaHaye RJ, Lang DD, Langley RA, Liew SL, Lu E, Mantz H, Manickam J, Mau TK, Medley S, Mikkelsen DR, Miller R, Monticello D, Morgan D, Moroz P, Motloch C, Mueller J, Myatt L, Nelson BE, Neumeyer CL, Nilson D, O'Conner T, Pearlstein LD, Peebles WA, Pelovitz M, Perkins FW, Perkins LJ, Petersen D, Pillsbury R, Politzer PA, Pomphrey N, Porkolab M, Posey A, Radovinsky A, Raftopoulis S, Ramakrishnan S, Ramos J, Rauch W, Ravenscroft D, Redler K, Reiersen WT, Reiman A, Reis E, Rewoldt G, Richards DJ, Rocco R, Rognlien TD, Ruzic D, Sabbagh S, Sapp J, Sayer RO, Scharer JE, Schmitz L, Schnitz J, Sevier L, Shipley SE, Simmons RT, Slack D, Smith GR, Stambaugh R, Steill G, Stevenson T, Stoenescu S, Onge KTS, Stotler DP, Strait T, Strickler DJ, Swain DW, Tang W, Tuszewski M, Ulrickson MA, VonHalle A, Walker MS, Wang C, Wang P, Warren J, Werley KA, West WP, Williams F, Wong R, Wright K, Wurden GA, Yugo JJ, Zakharov L, Zbasnik J. The design of the Tokamak Physics Experiment (TPX). J Fusion Energ 1993. [DOI: 10.1007/bf01079667] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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