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Zhou Y, Tong RH, Zhong WL, Tan Y, Jiang M, Shi ZB, Yang ZC, Shen YQ, Wen J, Liang AS. Quasi-optical design for the cross-polarization scattering diagnostic on the HL-3 tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:053507. [PMID: 38758767 DOI: 10.1063/5.0211022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 04/29/2024] [Indexed: 05/19/2024]
Abstract
As the plasma beta (β) increases in high-performance tokamaks, electromagnetic turbulence becomes more significant, potentially constraining their operational range. To investigate this turbulence, a cross-polarization scattering (CPS) diagnostic system is being developed on the HL-3 tokamak for simultaneous measurements of density and magnetic fluctuations. In this work, a quasi-optical system has been designed and analyzed for the Q-band CPS diagnostic. The system includes a lens group for beam waist size optimization, a rotatable wire-grid polarizer for polarization adjustment, and a reflector group for measurement range regulation and system response enhancement. Laboratory tests demonstrated a beam radius of order 4 cm at the target measurement location (near the plasma pedestal), cross-polarization isolation exceeding 30 dB, and poloidal and toroidal angle adjustment ranges of ±40° and ±15°, respectively. These results verify the system's feasibility through laboratory evaluations. The quasi-optical system has been installed on the HL-3 tokamak during the 2023 experimental campaign to support the development of CPS diagnostics.
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Affiliation(s)
- Y Zhou
- Southwestern Institute of Physics, Chengdu 610041, China
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - R H Tong
- Southwestern Institute of Physics, Chengdu 610041, China
| | - W L Zhong
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Y Tan
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - M Jiang
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Z B Shi
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Z C Yang
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Y Q Shen
- Southwestern Institute of Physics, Chengdu 610041, China
| | - J Wen
- Southwestern Institute of Physics, Chengdu 610041, China
| | - A S Liang
- Southwestern Institute of Physics, Chengdu 610041, China
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2
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Zhou Y, Tong R, Zhong W, Tan Y, Shi Z, Jiang M, Wen J, Yang Z, Shi P, Liang A, Yu X, Shen Y, Xue G, Deng W. Ray-tracing analysis for combined Doppler backscattering and cross-polarization scattering diagnostic on the HL-2M tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:013508. [PMID: 36725546 DOI: 10.1063/5.0126970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 12/27/2022] [Indexed: 06/18/2023]
Abstract
To measure plasma density and magnetic fluctuations on the HL-2M tokamak simultaneously, a new diagnostic system combining Doppler backscattering (DBS) and cross-polarization scattering (CPS) is under development. It is essential to understand the propagation of injected and scattered rays to support the electronic/quasi-optical design and subsequent interpretation of the detected signals of the multi-channel DBS/CPS measurements. Thus, ray-tracing analysis with the axisymmetric ray-tracing code BORAY has been performed to estimate the scattering location and wavenumbers of the density and magnetic fluctuations. In addition, the influence of accordance between toroidal and poloidal launch angles is investigated. The received DBS/CPS signal quality can be improved by matching the parallel wavenumber in the direction of magnetic field lines.
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Affiliation(s)
- Yu Zhou
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Ruihai Tong
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Wulyu Zhong
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Yi Tan
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Zhongbing Shi
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Min Jiang
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Jie Wen
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Zengchen Yang
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Peiwan Shi
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Anshu Liang
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Xin Yu
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Yuqi Shen
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Guanqun Xue
- Southwestern Institute of Physics, Chengdu 610041, China
| | - Weichu Deng
- Southwestern Institute of Physics, Chengdu 610041, China
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3
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Rhodes TL, Michael CA, Shi P, Scannell R, Storment S, Pratt Q, Lantsov R, Fitzgerald I, Hall-Chen VH, Crocker NA, Peebles WA. Design elements and first data from a new Doppler backscattering system on the MAST-U spherical tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113549. [PMID: 36461471 DOI: 10.1063/5.0101848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/25/2022] [Indexed: 06/17/2023]
Abstract
A new Doppler backscattering (DBS) system has been installed and tested on the MAST-U spherical tokamak. It utilizes eight simultaneous fixed frequency probe beams (32.5, 35, 37.5, 40, 42.5, 45, 47.5, and 50 GHz). These frequencies provide a range of radial positions from the edge plasma to the core depending on plasma conditions. The system utilizes a combination of novel features to provide remote control of the probed density wavenumber, the launched polarization (X vs O-mode), and the angle of the launched DBS to match the magnetic field pitch angle. The range of accessible density turbulence wavenumbers (kθ) is reasonably large with normalized wavenumbers kθρs ranging from ≤0.5 to 9 (ion sound gyroradius ρs = 1 cm). This wavenumber range is relevant to a variety of instabilities believed to be important in establishing plasma transport (e.g., ion temperature gradient, trapped electron, electron temperature gradient, micro-tearing, kinetic ballooning modes). The system is specifically designed to address the requirement of density fluctuation wavevector alignment which can significantly reduce the SNR if not accounted for.
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Affiliation(s)
- T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - C A Michael
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - P Shi
- UKAEA/CCFE, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB, UK
| | - R Scannell
- UKAEA/CCFE, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB, UK
| | - S Storment
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - Q Pratt
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - R Lantsov
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - I Fitzgerald
- UKAEA/CCFE, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB, UK
| | - V H Hall-Chen
- Institute of High Performance Computing, Singapore 138632, Singapore
| | - N A Crocker
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
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4
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Hong R, Rhodes TL, Wang G, Peebles WA. Ray-tracing analysis for cross-polarization scattering diagnostic on MAST-upgrade spherical tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:063505. [PMID: 34243511 DOI: 10.1063/5.0043600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 05/19/2021] [Indexed: 06/13/2023]
Abstract
A combined Doppler backscattering/cross-polarization scattering (DBS/CPS) system is being deployed on MAST-U for simultaneous measurements of local density turbulence, turbulence flows, and magnetic turbulence. In this design, CPS shares the probing beam with the DBS and uses a separate parallel-viewing receiver system. In this study, we utilize a modified GENRAY 3D ray-tracing code to simulate the propagation of the probing and scattered beams. The contributions of different scattering locations along the entire beam trajectories are considered, and the corresponding local B̃ wavenumbers are estimated using the wavevector matching criterion. The wavenumber ranges of the local B̃ that are detectable to the CPS system are explored for simulated L- and H-mode plasmas.
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Affiliation(s)
- R Hong
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - G Wang
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
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5
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Zhu Y, Yu JH, Yu G, Ye Y, Chen Y, Tobias B, Diallo A, Kramer G, Ren Y, Tang W, Dong G, Churchill R, Domier CW, Li X, Luo C, Chen M, Luhmann NC. System-on-chip upgrade of millimeter-wave imaging diagnostics for fusion plasma. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:053522. [PMID: 34243257 DOI: 10.1063/5.0040449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 04/23/2021] [Indexed: 06/13/2023]
Abstract
Monolithic, millimeter wave "system-on-chip" technology has been employed in chip heterodyne radiometers in a newly developed Electron Cyclotron Emission Imaging (ECEI) system on the DIII-D tokamak for 2D electron temperature and fluctuation diagnostics. The system employs 20 horn-waveguide receiver modules each with customized W-band (75-110 GHz) monolithic microwave integrated circuit chips comprising a W-band low noise amplifier, a balanced mixer, a ×2 local oscillator (LO) frequency doubler, and two intermediate frequency amplifier stages in each module. Compared to previous quasi-optical ECEI arrays with Schottky mixer diodes mounted on planar antennas, the upgraded W-band array exhibits >30 dB additional gain and 20× improvement in noise temperature; an internal eight times multiplier chain is used to provide LO coupling, thereby eliminating the need for quasi-optical coupling. The horn-waveguide shielding housing avoids out-of-band noise interference on each module. The upgraded ECEI system plays an important role for absolute electron temperature and fluctuation measurements for edge and core region transport physics studies. An F-band receiver chip (up to 140 GHz) is under development for additional fusion facilities with a higher toroidal magnetic field. Visualization diagnostics provide multi-scale and multi-dimensional data in plasma profile evolution. A significant aspect of imaging measurement is focusing on artificial intelligence for science applications.
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Affiliation(s)
- Y Zhu
- University of California Davis, Davis, California 95616, USA
| | - J-H Yu
- University of California Davis, Davis, California 95616, USA
| | - G Yu
- University of California Davis, Davis, California 95616, USA
| | - Y Ye
- University of California Davis, Davis, California 95616, USA
| | - Y Chen
- University of California Davis, Davis, California 95616, USA
| | - B Tobias
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - A Diallo
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - G Kramer
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - Y Ren
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - W Tang
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - G Dong
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Churchill
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - C W Domier
- University of California Davis, Davis, California 95616, USA
| | - X Li
- University of Science and Technology of China, Hefei, Anhui 230000, China
| | - C Luo
- University of California Davis, Davis, California 95616, USA
| | - M Chen
- University of California Davis, Davis, California 95616, USA
| | - N C Luhmann
- University of California Davis, Davis, California 95616, USA
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Ji JX, Liu AD, Zhou C, Zhuang G, Zhang J, Feng X, Liu ZY, Zhong XM, Fan HR, Zhang SB, Liu Y, Hu LQ, Mao WZ, Lan T, Xie JL, Li H, Liu ZX, Liu WD. The cross-polarization scattering system for the magnetic fluctuation measurement in the Experimental Advanced Superconducting Tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043511. [PMID: 34243396 DOI: 10.1063/5.0012520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 03/16/2021] [Indexed: 06/13/2023]
Abstract
The cross-polarization scattering (CPS) system for magnetic fluctuation measurements in the Experimental Advanced Superconducting Tokamak (EAST) has been designed and installed. Different from the Doppler reflectometer (DR) system, the CPS system detects the perpendicular polarization of the electromagnetic wave induced by magnetic fluctuations B̃. The CPS system in the EAST has been developed from the existing Doppler reflectometer system, and they are integrated together for simultaneous measurement of magnetic and density fluctuations. Ray-tracing simulations are used to calculate the scattering locations and the wavenumber coverage of the magnetic fluctuation for CPS. In the experiments, the CPS and DR system data were different in Doppler shift, amplitude, and spectrum broadening. In this article, the hardware design, the ray tracing, and the preliminary results of the system in the EAST are presented.
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Affiliation(s)
- J X Ji
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - A D Liu
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - C Zhou
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - G Zhuang
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - J Zhang
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - X Feng
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Z Y Liu
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - X M Zhong
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - H R Fan
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - S B Zhang
- Institute of Plasma Physics, Chinese Academy of Sciences, Anhui, Hefei 230021, China
| | - Y Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Anhui, Hefei 230021, China
| | - L Q Hu
- Institute of Plasma Physics, Chinese Academy of Sciences, Anhui, Hefei 230021, China
| | - W Z Mao
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - T Lan
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - J L Xie
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - H Li
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Z X Liu
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - W D Liu
- School of Nuclear Sciences and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
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7
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Wang G, Rhodes TL, Crocker NA, Peebles WA, Barada K. First step toward a synthetic diagnostic for magnetic fluctuation measurements using cross-polarization scattering on DIII-D. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H113. [PMID: 30399840 DOI: 10.1063/1.5036791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/15/2018] [Indexed: 06/08/2023]
Abstract
Cross-polarization scattering (CPS) provides localized magnetic fluctuation ( B ̃ ) measurements in fusion plasmas based on the process where B ̃ scatters electromagnetic radiation into the orthogonal polarization. The CPS system on DIII-D utilizes the probe beam of a Doppler backscattering (DBS) diagnostic combined with a cross-view CPS receiver system, which allows simultaneous density and B ̃ measurements with good spatial and wavenumber coverage. The interpretation of the signals is challenging due to the complex plasma propagation of the DBS probe beam and CPS receive beams. A synthetic diagnostic for CPS is therefore essential to interpret data and perform detailed validation tests of non-linear turbulence simulations. This work reports a first step toward a synthetic diagnostic for CPS utilizing GENRAY, a 3-D ray tracing code, to simulate the propagation of the probe and scattered rays. The local B ̃ wavenumber is calculated from the local O- and X-mode wavenumbers using the wave vector matching scattering condition. The CPS wavenumber values and spatial locations are determined by a complex consideration that includes the local density and B ̃ level, receive antenna pattern and orientation, scattering volume, wavenumber values detected at the various scattering centers, and alignment of the magnetic wave vector with the plane perpendicular to the magnetic field. The issue of a spurious CPS signal due to polarization mismatches for launch and receive is also discussed. It is suggested that simultaneous O- and X-mode DBS measurements should be utilized for better understanding of the CPS signal contamination when the cutoff locations for both polarizations are close.
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Affiliation(s)
- G Wang
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - N A Crocker
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
| | - K Barada
- Physics and Astronomy Department, University of California, Los Angeles, California 90095, USA
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8
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Rhodes TL, Lantsov R, Wang G, Ellis R, Peebles WA. Optimized quasi-optical cross-polarization scattering system for the measurement of magnetic turbulence on the DIII-D tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H107. [PMID: 30399735 DOI: 10.1063/1.5035427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 06/04/2018] [Indexed: 06/08/2023]
Abstract
Simulations and laboratory tests are used to design and optimize a quasi-optical system for cross-polarization scattering (CPS) measurements of magnetic turbulence on the DIII-D tokamak. The CPS technique uses a process where magnetic turbulence scatters electromagnetic radiation into the perpendicular polarization enabling a local measurement of the perturbing magnetic fluctuations. This is a challenging measurement that addresses the contribution of magnetic turbulence to anomalous thermal transport in fusion research relevant plasmas. The goal of the new quasi-optical design is to demonstrate the full spatial and wavenumber capabilities of the CPS diagnostic. The approach used consists of independently controlled and in vacuo aiming systems for the probe and scattered beams (55-75 GHz).
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Affiliation(s)
- T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - R Lantsov
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - G Wang
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - R Ellis
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
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9
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Schmitz L, Deng B, Thompson M, Gota H, Lau C, Fulton DP, Lin Z, Tajima T, Binderbauer M. Combination Doppler backscattering/cross-polarization scattering diagnostic for the C-2W field-reversed configuration. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:10H116. [PMID: 30399746 DOI: 10.1063/1.5038914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/20/2018] [Indexed: 06/08/2023]
Abstract
A versatile combination Doppler backscattering and Cross-Polarization Scattering (CPS) diagnostic for the C-2W beam-driven field-reversed configuration is described. This system is capable of measuring density fluctuations and perpendicular magnetic field fluctuations across a wide wavenumber range (2.5 ≤ k θ ρ s ≤ 50), with typical resolution Δk θ/k θ ≤ 0.4-0.8. Four tunable frequencies (26 GHz ≤ f ≤ 60 GHz corresponding to plasma cut-off densities 0.8 × 1019 ≤ n e ≤ 4.4 × 1019 m-3) are launched via quasi-optical beam combiners/polarizers and an adjustable parabolic focusing mirror selecting the beam incidence angle. GENRAY ray tracing shows that the incident O-mode and backscattered CPS X-mode beam trajectories for C-2W plasma parameters nearly overlap, allowing simultaneous detection of ñ and B̃ r or B̃ θ from essentially the same scattering volume.
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Affiliation(s)
- L Schmitz
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - B Deng
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - M Thompson
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - H Gota
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - C Lau
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - D P Fulton
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - Z Lin
- Department of Physics and Astronomy, University of California Irvine, Irvine, California 92697, USA
| | - T Tajima
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
| | - M Binderbauer
- TAE Technologies, Inc., Foothill Ranch, California 92610, USA
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10
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Affiliation(s)
- A.J.H. Donné
- FOM-Institute for Plasma Physics Rijnhuizen P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands, Tel. +49 2461 61 3655 / +31 653 798 329, Fax +49 2461 61 4038, e-mail:
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11
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Sabot R, Hennequin P, Colas L. Fluctuation Measurements and Their Link with Transport on Tore Supra. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst09-a9176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. Sabot
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - P. Hennequin
- Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, 91128 Palaiseau, France
| | - L. Colas
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
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12
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Hoang GT. Key Role of the Current Density Profile on Core Confinement and Transport in Tore Supra Plasmas: Electron Heat and Particle Transport. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst09-a9185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. T. Hoang
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
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13
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Luhmann NC, Bindslev H, Park H, Sánchez J, Taylor G, Yu CX. Chapter 3: Microwave Diagnostics. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst08-a1675] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | - H. Park
- Princeton Plasma Physics Laboratory, Princeton, New Jersey
| | | | - G. Taylor
- Princeton Plasma Physics Laboratory, Princeton, New Jersey
| | - C. X. Yu
- University of Science and Technology of China, Hefei, China
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14
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Rhodes TL, Barada K, Peebles WA, Crocker NA. Simultaneous measurement of magnetic and density fluctuations via cross-polarization scattering and Doppler backscattering on the DIII-D tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E726. [PMID: 27910380 DOI: 10.1063/1.4960601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An upgraded cross-polarization scattering (CPS) system for the simultaneous measurement of internal magnetic fluctuations B̃ and density fluctuations ñ is presented. The system has eight radial quadrature channels acquired simultaneously with an eight-channel Doppler backscattering system (measures density fluctuations ñ and flows). 3-D ray tracing calculations based on the GENRAY ray tracing code are used to illustrate the scattering and geometric considerations involved in the CPS implementation on DIII-D. A unique quasi-optical design and IF electronics system allow direct comparison of B̃ and ñ during dynamic or transient plasma events (e.g., Edge Localized Modes or ELMs, L to H-mode transitions, etc.). The system design allows the interesting possibility of both magnetic-density (B̃-ñ) fluctuation and magnetic-temperature (B̃-T̃) fluctuation cross-phase measurements suitable for detailed tests of turbulence simulations.
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Affiliation(s)
- T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - K Barada
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - N A Crocker
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
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15
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Barada K, Rhodes TL, Crocker NA, Peebles WA. Measurement of local, internal magnetic fluctuations via cross-polarization scattering in the DIII-D tokamak (invited). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E601. [PMID: 27910576 DOI: 10.1063/1.4960154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present new measurements of internal magnetic fluctuations obtained with a novel eight channel cross polarization scattering (CPS) system installed on the DIII-D tokamak. Measurements of internal, localized magnetic fluctuations provide a window on an important physics quantity that we heretofore have had little information on. Importantly, these measurements provide a new ability to challenge and test linear and nonlinear simulations and basic theory. The CPS method, based upon the scattering of an incident microwave beam into the opposite polarization by magnetic fluctuations, has been significantly extended and improved over the method as originally developed on the Tore Supra tokamak. A new scattering geometry, provided by a unique probe beam, is utilized to improve the spatial localization and wavenumber range. Remotely controllable polarizer and mirror angles allow polarization matching and wavenumber selection for a range of plasma conditions. The quasi-optical system design, its advantages and challenges, as well as important physics validation tests are presented and discussed. Effect of plasma beta (ratio of kinetic to magnetic pressure) on both density and magnetic fluctuations is studied and it is observed that internal magnetic fluctuations increase with beta. During certain quiescent high confinement operational regimes, coherent low frequency modes not detected by magnetic probes are detected locally by CPS diagnostics.
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Affiliation(s)
- K Barada
- University of California-Los Angeles, P.O. Box 957099, Los Angeles, California 90095, USA
| | - T L Rhodes
- University of California-Los Angeles, P.O. Box 957099, Los Angeles, California 90095, USA
| | - N A Crocker
- University of California-Los Angeles, P.O. Box 957099, Los Angeles, California 90095, USA
| | - W A Peebles
- University of California-Los Angeles, P.O. Box 957099, Los Angeles, California 90095, USA
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16
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Chen J, Ding WX, Brower DL, Finkenthal D, Muscatello C, Taussig D, Boivin R. Faraday-effect polarimeter diagnostic for internal magnetic field fluctuation measurements in DIII-D. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11E108. [PMID: 27910426 DOI: 10.1063/1.4960056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Motivated by the need to measure fast equilibrium temporal dynamics, non-axisymmetric structures, and core magnetic fluctuations (coherent and broadband), a three-chord Faraday-effect polarimeter-interferometer system with fast time response and high phase resolution has recently been installed on the DIII-D tokamak. A novel detection scheme utilizing two probe beams and two detectors for each chord results in reduced phase noise and increased time response [δb ∼ 1G with up to 3 MHz bandwidth]. First measurement results were obtained during the recent DIII-D experimental campaign. Simultaneous Faraday and density measurements have been successfully demonstrated and high-frequency, up to 100 kHz, Faraday-effect perturbations have been observed. Preliminary comparisons with EFIT are used to validate diagnostic performance. Principle of the diagnostic and first experimental results is presented.
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Affiliation(s)
- J Chen
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - W X Ding
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - D L Brower
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | - D Finkenthal
- Palomar Scientific Instruments, San Marcos, California 92069, USA
| | - C Muscatello
- General Atomics, San Diego, California 92186, USA
| | - D Taussig
- General Atomics, San Diego, California 92186, USA
| | - R Boivin
- General Atomics, San Diego, California 92186, USA
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17
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Rhodes TL, Peebles WA, Crocker NA, Nguyen X. Development of a cross-polarization scattering system for the measurement of internal magnetic fluctuations in the DIII-D tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:11D838. [PMID: 25430251 DOI: 10.1063/1.4887276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The design and performance of a new cross-polarization scattering (CPS) system for the localized measurement of internal magnetic fluctuations is presented. CPS is a process whereby magnetic fluctuations scatter incident electromagnetic radiation into a perpendicular polarization which is subsequently detected. A new CPS design that incorporates a unique scattering geometry was laboratory tested, optimized, and installed on the DIII-D tokamak. Plasma tests of signal-to-noise, polarization purity, and frequency response indicate proper functioning of the system. CPS data show interesting features related to internal MHD perturbations known as sawteeth that are not observed on density fluctuations.
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Affiliation(s)
- T L Rhodes
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - W A Peebles
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - N A Crocker
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
| | - X Nguyen
- Physics and Astronomy Department, University of California, Los Angeles, California 90098, USA
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18
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Affiliation(s)
- A.J.H. Donné
- FOM-Institute for Plasma Physics Rijnhuizen P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands, Tel. +49 2461 61 3655 / +31 653 798 329, Fax +49 2461 61 4038, e-mail:
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19
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Entrop I, Jaspers R, Finken KH. Scale size of magnetic turbulence in tokamaks probed with 30-MeV electrons. PHYSICAL REVIEW LETTERS 2000; 84:3606-3609. [PMID: 11019157 DOI: 10.1103/physrevlett.84.3606] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/1999] [Indexed: 05/23/2023]
Abstract
Measurements of synchrotron radiation emitted by 30-MeV runaway electrons in the TEXTOR-94 tokamak show that the runaway population decays after switching on neutral beam injection (NBI). The decay starts only with a significant delay, which decreases with increasing NBI heating power. This delay provides direct evidence of the energy dependence of runaway confinement, which is expected if magnetic modes govern the loss of runaways. Application of the theory by Mynick and Strachan [Phys. Fluids 24, 695 (1981)] yields estimates for the "mode width" (delta) of magnetic perturbations: delta<0.5 cm in Ohmic discharges, increasing to delta = 4.4 cm for 0. 6 MW NBI.
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Affiliation(s)
- I Entrop
- FOM-Instituut voor Plasmafysica "Rijnhuizen," Association Euratom-FOM, P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands
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20
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Reflectometric measurement of density and magnetic fluctuations in CRF-driven waves. FUSION ENGINEERING AND DESIGN 1997. [DOI: 10.1016/s0920-3796(96)00651-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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