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McCarthy W, Golfinopoulos T, Woller KB, Vincent C, Kuang A, Labombard B. First application of a digital mirror Langmuir probe for real-time plasma diagnosis. Rev Sci Instrum 2021; 92:103502. [PMID: 34717421 DOI: 10.1063/5.0057318] [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: 05/19/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
For the first time, a digital Mirror Langmuir Probe (MLP) has successfully sampled plasma temperature, ion saturation current, and floating potential together on a single probe tip in real time in a radio-frequency driven helicon linear plasma device. This is accomplished by feedback control of the bias sweep to ensure a good fit to I-V characteristics with a high frequency, high power digital amplifier, and field-programmable gate array controller. Measurements taken by the MLP were validated by a low speed I-V characteristic manually collected during static plasma conditions. Plasma fluctuations, induced by varying the axial magnetic field (f̃ = 10 Hz), were also successfully monitored with the MLP. Further refinement of the digital MLP pushes it toward a turn-key system that minimizes the time to deployment and lessens the learning curve, positioning the digital MLP as a capable diagnostic for the study of low radio-frequency plasma physics. These demonstrations bolster confidence in fielding such digital MLP diagnostics in magnetic confinement experiments with high spatial and adequate temporal resolution, such as edge plasma, scrape-off layer, and divertor probes.
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Affiliation(s)
- W McCarthy
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - T Golfinopoulos
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - K B Woller
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - C Vincent
- United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB, United Kingdom
| | - A Kuang
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
| | - B Labombard
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, 77 Massachusetts Ave., Cambridge, Massachusetts 02139, USA
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Bonoli PT, Parker R, Wukitch SJ, Lin Y, Porkolab M, Wright JC, Edlund E, Graves T, Lin L, Liptac J, Parisot A, Schmidt AE, Tang V, Beck W, Childs R, Grimes M, Gwinn D, Johnson D, Irby J, Kanojia A, Koert P, Marazita S, Marmar E, Terry D, Vieira R, Wallace G, Zaks J, Bernabei S, Brunkhorse C, Ellis R, Fredd E, Greenough N, Hosea J, Kung CC, Loesser GD, Rushinski J, Schilling G, Phillips CK, Wilson JR, Harvey RW, Fiore CL, Granetz R, Greenwald M, Hubbard AE, Hutchinson IH, Labombard B, Lipschultz B, Rice J, Snipes JA, Terry J, Wolfe SM. Wave-Particle Studies in the Ion Cyclotron and Lower Hybrid Ranges of Frequencies in Alcator C-Mod. Fusion Science and Technology 2017. [DOI: 10.13182/fst07-a1430] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [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)
- P. T. Bonoli
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - R. Parker
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - S. J. Wukitch
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - Y. Lin
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - M. Porkolab
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. C. Wright
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - E. Edlund
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - T. Graves
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - L. Lin
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. Liptac
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - A. Parisot
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - A. E. Schmidt
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - V. Tang
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - W. Beck
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - R. Childs
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - M. Grimes
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - D. Gwinn
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - D. Johnson
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. Irby
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - A. Kanojia
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - P. Koert
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - S. Marazita
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - E. Marmar
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - D. Terry
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - R. Vieira
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - G. Wallace
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. Zaks
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - S. Bernabei
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - C. Brunkhorse
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - R. Ellis
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - E. Fredd
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - N. Greenough
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - J. Hosea
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - C. C. Kung
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - G. D. Loesser
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - J. Rushinski
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - G. Schilling
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - C. K. Phillips
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | - J. R. Wilson
- Princeton University, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
| | | | - C. L. Fiore
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - R. Granetz
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - M. Greenwald
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - A. E. Hubbard
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - I. H. Hutchinson
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - B. Labombard
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - B. Lipschultz
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. Rice
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. A. Snipes
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - J. Terry
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
| | - S. M. Wolfe
- Massachusetts Institute of Technology, Plasma Science and Fusion Center, Cambridge, Massachusetts 02139
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Diallo A, Hughes JW, Greenwald M, Labombard B, Davis E, Baek SG, Theiler C, Snyder P, Canik J, Walk J, Golfinopoulos T, Terry J, Churchill M, Hubbard A, Porkolab M, Delgado-Aparicio L, Reinke ML, White A. Observation of edge instability limiting the pedestal growth in tokamak plasmas. Phys Rev Lett 2014; 112:115001. [PMID: 24702380 DOI: 10.1103/physrevlett.112.115001] [Citation(s) in RCA: 3] [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] [Received: 10/15/2013] [Indexed: 06/03/2023]
Abstract
With fusion device performance hinging on the edge pedestal pressure, it is imperative to experimentally understand the physical mechanism dictating the pedestal characteristics and to validate and improve pedestal predictive models. This Letter reports direct evidence of density and magnetic fluctuations showing the stiff onset of an edge instability leading to the saturation of the pedestal on the Alcator C-Mod tokamak. Edge stability analyses indicate that the pedestal is unstable to both ballooning mode and kinetic ballooning mode in agreement with observations.
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Affiliation(s)
- A Diallo
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - J W Hughes
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - M Greenwald
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - B Labombard
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - E Davis
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - S-G Baek
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - C Theiler
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - P Snyder
- General Atomics, San Diego, California 92186, USA
| | - J Canik
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J Walk
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - T Golfinopoulos
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Terry
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - M Churchill
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A Hubbard
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - M Porkolab
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | - M L Reinke
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A White
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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