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Han W, Pietersen RA, Villamor-Lora R, Beveridge M, Offeddu N, Golfinopoulos T, Theiler C, Terry JL, Marmar ES, Drori I. Tracking blobs in the turbulent edge plasma of a tokamak fusion device. Sci Rep 2022; 12:18142. [PMID: 36307455 PMCID: PMC9616937 DOI: 10.1038/s41598-022-21671-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/29/2022] [Indexed: 11/09/2022] Open
Abstract
The analysis of turbulence in plasmas is fundamental in fusion research. Despite extensive progress in theoretical modeling in the past 15 years, we still lack a complete and consistent understanding of turbulence in magnetic confinement devices, such as tokamaks. Experimental studies are challenging due to the diverse processes that drive the high-speed dynamics of turbulent phenomena. This work presents a novel application of motion tracking to identify and track turbulent filaments in fusion plasmas, called blobs, in a high-frequency video obtained from Gas Puff Imaging diagnostics. We compare four baseline methods (RAFT, Mask R-CNN, GMA, and Flow Walk) trained on synthetic data and then test on synthetic and real-world data obtained from plasmas in the Tokamak à Configuration Variable (TCV). The blob regime identified from an analysis of blob trajectories agrees with state-of-the-art conditional averaging methods for each of the baseline methods employed, giving confidence in the accuracy of these techniques. By making a dataset and benchmark publicly available, we aim to lower the entry barrier to tokamak plasma research, thereby greatly broadening the community of scientists and engineers who might apply their talents to this endeavor.
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Affiliation(s)
- Woonghee Han
- MIT Plasma Science and Fusion Center, Cambridge, MA, 02139, USA.
| | | | | | - Matthew Beveridge
- MIT Computer Science & Artificial Intelligence Laboratory (CSAIL), Cambridge, MA, 02139, USA
| | - Nicola Offeddu
- École Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), 1015, Lausanne, Switzerland
| | | | - Christian Theiler
- École Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), 1015, Lausanne, Switzerland
| | - James L Terry
- MIT Plasma Science and Fusion Center, Cambridge, MA, 02139, USA
| | - Earl S Marmar
- MIT Plasma Science and Fusion Center, Cambridge, MA, 02139, USA
| | - Iddo Drori
- MIT Computer Science & Artificial Intelligence Laboratory (CSAIL), Cambridge, MA, 02139, USA
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2
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Kajita S, Iwai S, Tanaka H, Nishijima D, Fujii K, van der Meiden H, Ohno N. Use of machine learning for a helium line intensity ratio method in Magnum-PSI. NUCLEAR MATERIALS AND ENERGY 2022. [DOI: 10.1016/j.nme.2022.101281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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3
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Nishizawa T, Griener M, Dux R, Grenfell G, Wendler D, Kado S, Manz P, Cavedon M. Linearized spectrum correlation analysis for thermal helium beam diagnostics. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103501. [PMID: 34717377 DOI: 10.1063/5.0062436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
We introduce a new correlation analysis technique for thermal helium beam (THB) diagnostics. Instead of directly evaluating line ratios from fluctuating time series, we apply arithmetic operations to all available He I lines and construct time series with desired dependencies on the plasma parameters. By cross-correlating those quantities and by evaluating ensemble averages, uncorrelated noise contributions can be removed. Through the synthetic data analysis, we demonstrate that the proposed analysis technique is capable of providing the power spectral densities of meaningful plasma parameters, such as the electron density and the electron temperature, even under low-photon-count conditions. In addition, we have applied this analysis technique to the experimental THB data obtained at the ASDEX Upgrade tokamak and successfully resolved the electron density and temperature fluctuations up to 90 kHz in a reactor relevant high power scenario.
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Affiliation(s)
- T Nishizawa
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Griener
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - R Dux
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - G Grenfell
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - D Wendler
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - S Kado
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0 011, Japan
| | - P Manz
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Cavedon
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
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Agostini M, Scarin P, Milazzo R, Cervaro V, Ghiraldelli R. Development and characterization of thermal helium beam diagnostic with four helium lines for RFX-mod2 experiment. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:113503. [PMID: 33261442 DOI: 10.1063/5.0023310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/01/2020] [Indexed: 06/12/2023]
Abstract
Thermal Helium Beam (THB) diagnostic is widely used for measuring the electron density and temperature in the boundary region of fusion plasmas, edges, and scrape-off layers. In its standard configuration, it measures three HeI lines (667.8 nm, 706.5 nm, and 728.1 nm) and, by using a collisional-radiative model, evaluates ne and Te from the ratios of their intensities. At large neutral He density (n0 ≳ 1017 m-3), radiation re-absorption is not negligible and it has to be taken into account; it can be estimated by measuring the intensity of the fourth HeI line, λ = 501.6 nm. The original THB diagnostic of the RFX-mod experiment has been upgraded, setting up the fourth line intensity acquisition. A Czerny-Turner spectrograph separates the lines, and the old multichannel photomultiplier (PMT) detectors are replaced with the new Multi-Pixel Photon Counter (MPPC). Two 16-channel MPPC array modules allow the observation of 32 signals (4 lines × 8 spatial points). Since the MPPCs are not sensitive to the magnetic field, the whole system can be installed near the experimental device, allowing a large reduction in the optical fibers' length with a gain in the collected signal intensity. This new THB will be installed in the new experiment RFX-mod2, the upgrade of the RFX-mod device. The RFX-mod2 will operate as both reversed field pinch and tokamak, and the goal of the THB is the evaluation of the edge electron density and temperature profiles in the two magnetic configurations, in D or H plasmas. This paper describes the system, the performance of the MPPC compared with the PMTs, the alignment, and the calibration.
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Affiliation(s)
- M Agostini
- Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy
| | - P Scarin
- Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy
| | - R Milazzo
- Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy
| | - V Cervaro
- Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy
| | - R Ghiraldelli
- Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova, Italy
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Griener M, Wolfrum E, Cavedon M, Dux R, Rohde V, Sochor M, Muñoz Burgos JM, Schmitz O, Stroth U. Helium line ratio spectroscopy for high spatiotemporal resolution plasma edge profile measurements at ASDEX Upgrade (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10D102. [PMID: 30399953 DOI: 10.1063/1.5034446] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The thermal helium beam edge diagnostic has recently been upgraded at the ASDEX Upgrade (AUG) tokamak experiment. Line ratio spectroscopy on neutral helium is a valuable tool for simultaneous determination of the electron temperature and density of plasmas. The diagnostic now offers a temporal resolution of 900 kHz with a spatial resolution of up to 3 mm at 32 lines of sight (LOS) simultaneously. The LOS covers a radial region of 8.5 cm, starting at the limiter radius and reaching into the confined region beyond the separatrix. Two components are of particular importance for the aforementioned hardware improvements. The first is the optical head, which collects the light from the experiment. Equipped with an innovative clamping system for optical fiber ends, an arbitrary distribution pattern of LOS can be achieved to gain radial and poloidal profiles. The second major development is a new polychromator system that measures the intensity of the 587 nm, 667 nm, 706 nm, and 728 nm helium lines simultaneously for 32 channels with filter-photomultiplier tube arrays. Thus, the thermal helium beam diagnostic supplements the AUG edge diagnostics, offering fast and spatially highly resolved electron temperature and density profile measurements that cover the plasma edge and scrape-off layer region. Plasma fluctuations, edge localized modes, filaments, and other turbulent structures are resolved, allowing analysis of their frequency and localization or their propagation velocity.
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Affiliation(s)
- M Griener
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - E Wolfrum
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Cavedon
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - R Dux
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - V Rohde
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Sochor
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
| | - J M Muñoz Burgos
- Astro Fusion Spectre, LLC, 11263 Avenida de los Lobos, Unit D, San Diego, California 92127, USA
| | - O Schmitz
- Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - U Stroth
- Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany
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Boundary plasma response in RFX-mod to 3D magnetic field perturbations. NUCLEAR MATERIALS AND ENERGY 2017. [DOI: 10.1016/j.nme.2017.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Zweben SJ, Terry JL, Stotler DP, Maqueda RJ. Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:041101. [PMID: 28456269 DOI: 10.1063/1.4981873] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Gas puff imaging (GPI) is a diagnostic of plasma turbulence which uses a puff of neutral gas at the plasma edge to increase the local visible light emission for improved space-time resolution of plasma fluctuations. This paper reviews gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion research, with a focus on the instrumentation, diagnostic cross-checks, and interpretation issues. The gas puff imaging hardware, optics, and detectors are described for about 10 GPI systems implemented over the past ∼15 years. Comparison of GPI results with other edge turbulence diagnostic results is described, and many common features are observed. Several issues in the interpretation of GPI measurements are discussed, and potential improvements in hardware and modeling are suggested.
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Affiliation(s)
- S J Zweben
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - J L Terry
- MIT, Cambridge, Massachusetts 02139, USA
| | - D P Stotler
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - R J Maqueda
- X Science LLC, Plainsboro, New Jersey 08536, USA
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