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Choe M, Oh D, Bak JG, Baek GW, Sung C. Development of a diamagnetic loop in KAIMIR. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2024; 95:073501. [PMID: 38949464 DOI: 10.1063/5.0212548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 06/11/2024] [Indexed: 07/02/2024]
Abstract
We developed a diamagnetic loop for the estimation of plasma stored energy in the KAIST Magnetic Mirror magnetic mirror device [Oh et al., J. Plasma Phys. 90, 975900202 (2024)]. Diamagnetic loops are used to estimate the plasma stored energy from measurements of the diamagnetic flux in plasma with an applied external magnetic field. However, diamagnetic flux measurements are accompanied by the vacuum flux, which generally exceeds the diamagnetic flux by over 10 000 times. Therefore, it is critical to attain a high signal-to-noise ratio with minimized noise in diamagnetic flux measurements. In this study, we employed a novel method to reduce background noise and improve the signal-to-noise ratio. Using two identical loops with opposite polarities, we successfully removed parasitic capacitive noise from the external insulation while amplifying the inductive signal two times. To eliminate the vacuum flux, we utilized two coaxial loops with different radii positioned at the same axial location. Results obtained from six paired loops confirmed the successful removal of the vacuum flux. The plasma stored energy was also found to agree well with Langmuir probe measurements, which verifies the diamagnetic flux measurements using the developed loop.
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Affiliation(s)
- M Choe
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - D Oh
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - J G Bak
- Korea Institute of Fusion Energy, Daejeon 34133, Republic of Korea
| | - G W Baek
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - C Sung
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
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Jia T, He K, Chen D, Qian J, Gu X, Shen B, Sun Y, Shi T, Wang Y, Zhang B, Gong X. The measurements by diamagnetic loops in EAST. FUSION ENGINEERING AND DESIGN 2022. [DOI: 10.1016/j.fusengdes.2022.113091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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3
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Inoue S. Calculation of diamagnetic β and l by using Cauchy Condition Surface scheme. FUSION ENGINEERING AND DESIGN 2021. [DOI: 10.1016/j.fusengdes.2021.112401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Han H, In Y, Kim J, Bak J, Hahn S, Jeon Y, Lee J, Yoon S. Detection of slowly rotating n = 1 mode with signal compensation for an externally perturbed field in the KSTAR tokamak. FUSION ENGINEERING AND DESIGN 2019. [DOI: 10.1016/j.fusengdes.2019.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Pustovitov V. Extended theory of diamagnetic measurements with account of the wall currents in tokamaks. FUSION ENGINEERING AND DESIGN 2019. [DOI: 10.1016/j.fusengdes.2018.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Giannone L, Fischer R, Fuchs JC, Geiger B, Maraschek M, Rittich D, Sieglin B, Bock A, Hobirk J, Kallenbach A, Mertens V, Schuhbeck KH, McCarthy PJ. Note: Internal diamagnetic flux measurements on ASDEX Upgrade. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:106101. [PMID: 30399901 DOI: 10.1063/1.5045543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
Internal diamagnetic flux measurements, with measurement loops and compensation magnetic probes inside the vacuum vessel, are now available on the ASDEX Upgrade tokamak. The measured diamagnetic flux is compared to that predicted by simulations and calculated from equilibrium reconstruction. The diamagnetic flux measured at 2 positions separated toroidally by 180° in the vacuum vessel is compared.
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Affiliation(s)
- L Giannone
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - R Fischer
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - J C Fuchs
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - B Geiger
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - M Maraschek
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - D Rittich
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - B Sieglin
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - A Bock
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - J Hobirk
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - A Kallenbach
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - V Mertens
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - K H Schuhbeck
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - P J McCarthy
- Department of Physics, University College Cork, Cork T12 YN60, Ireland
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Yang J, Kim Y, Jeong WI, Hwang YS. Simple and accurate method of diamagnetic flux measurement in Versatile Experimental Spherical Torus (VEST). THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:103508. [PMID: 30399825 DOI: 10.1063/1.5041517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 10/03/2018] [Indexed: 06/08/2023]
Abstract
Diamagnetic flux is measured accurately in the Versatile Experiment Spherical Torus by simply measuring the change in the toroidal field (TF) coil current without additional poloidal loops. Stray couplings mainly with the plasma current (since poloidal field coils are aligned well to the TF coils) are compensated for, resulting in the minimum measurable flux of ±0.2 mWb determined mainly by the finite sensitivity of the TF coil current sensor, implying that the accuracy of this simple method can be improved by measuring the TF coil current change with a higher sensitivity. The poloidal beta is derived from the measured diamagnetic flux with the consideration of the low aspect ratio geometry. The poloidal beta and the plasma stored energy derived from the measurement are in good agreement with those from the equilibrium reconstruction, and the energy confinement time derived from the measurement is consistent with the L mode scaling.
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Affiliation(s)
- J Yang
- Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea
| | - Y Kim
- Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea
| | - W I Jeong
- Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea
| | - Y S Hwang
- Department of Nuclear Engineering, Seoul National University, Seoul 151-744, South Korea
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Kim HS, Bak JG, Hahn SH. Improvements of magnetic measurements for plasma control in KSTAR tokamak. FUSION ENGINEERING AND DESIGN 2017. [DOI: 10.1016/j.fusengdes.2017.02.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Zhu LZ, Chen ZP, Li FM, Liu H, Chen ZY, Zhuang G. Diamagnetic measurements based on the compensation of TF current diffusion in J-TEXT. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:11D420. [PMID: 27910511 DOI: 10.1063/1.4960413] [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
Due to the existence both of toroidal ripples and toroidal field (TF) current diffusion, the toroidal flux changes with time when the TF current is at the flat-top. A diamagnetic measurement based on the compensation of TF current diffusion has been built in J-TEXT to solve this problem. The measurement system includes a double-loop installed in the vacuum vessel and an array of small printed circuit board (PCB) magnetic probes placed on the mid-plane of one TF coil. A model was proposed to analyze and compensate the effect of TF current diffusion. Experiment results show that the residual flux is about 1 × 10-4 Wb after the compensation and it can meet the need of diamagnetic measurement in J-TEXT.
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Affiliation(s)
- L Z Zhu
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Z P Chen
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - F M Li
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - H Liu
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Z Y Chen
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - G Zhuang
- State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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Giannone L, Geiger B, Bilato R, Maraschek M, Odstrčil T, Fischer R, Fuchs JC, McCarthy PJ, Mertens V, Schuhbeck KH. Real-time diamagnetic flux measurements on ASDEX Upgrade. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:053509. [PMID: 27250425 DOI: 10.1063/1.4950858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Real-time diamagnetic flux measurements are now available on ASDEX Upgrade. In contrast to the majority of diamagnetic flux measurements on other tokamaks, no analog summation of signals is necessary for measuring the change in toroidal flux or for removing contributions arising from unwanted coupling to the plasma and poloidal field coil currents. To achieve the highest possible sensitivity, the diamagnetic measurement and compensation coil integrators are triggered shortly before plasma initiation when the toroidal field coil current is close to its maximum. In this way, the integration time can be chosen to measure only the small changes in flux due to the presence of plasma. Two identical plasma discharges with positive and negative magnetic field have shown that the alignment error with respect to the plasma current is negligible. The measured diamagnetic flux is compared to that predicted by TRANSP simulations. The poloidal beta inferred from the diamagnetic flux measurement is compared to the values calculated from magnetic equilibrium reconstruction codes. The diamagnetic flux measurement and TRANSP simulation can be used together to estimate the coupled power in discharges with dominant ion cyclotron resonance heating.
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Affiliation(s)
- L Giannone
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - B Geiger
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - R Bilato
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - M Maraschek
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - T Odstrčil
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - R Fischer
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - J C Fuchs
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - P J McCarthy
- Department of Physics, University College Cork, Cork T12 YN60, Ireland
| | - V Mertens
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
| | - K H Schuhbeck
- Max Planck Institute for Plasma Physics, 85748 Garching, Germany
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Ji XQ, Yang QW, Xu Y, Sun TF, Yuan BS, Feng BB, Liu Y, Cui ZY, Lu J. Diamagnetic measurements by concentric loops in the HL-2A tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:083507. [PMID: 24007065 DOI: 10.1063/1.4816842] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The diamagnetic concentric loop method in the HL-2A tokamak is described in this article. The system consists of two concentric poloidal loops with different areas enclosing the plasma column and a short time constant differential integrator, RC < 1 ms. The diamagnetic flux in HL-2A ranges from 1 mWb to 2 mWb for typical discharges with plasma current Ip = 100-400 kA. The integrator output ranges from 0.1 V to 0.2 V with time constant RC = 0.5 ms, and differential area ΔS∕Sout ≈ 7%. Using hybrid analog-digital compensation, the integration drift can be well compensated within 5 mV∕10 s, which can meet the requirement of the concentric loop system. In this method, the measurement of differential area ΔS is not required. The vacuum toroidal flux can be compensated by adjusting the resistance in the integration circuit for several discharges with toroidal field only, which minimizes the additional error produced by a measurement of differential area. The diamagnetic concentric loop system improved the signal to noise ratio by using the short time constant integration. The system with a resolution of ±0.2 kJ can be used to study rapid changes in plasma stored energy, such as the additional power absorbed by the plasma, and the energy loss caused by edge localized modes.
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Affiliation(s)
- X Q Ji
- Southwestern Institute of Physics, Chengdu, Sichuan 610041, China
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Jeong SH, Chang DH, Kim TS, In SR, Lee KW, Jin JT, Chang DS, Oh BH, Bae YS, Kim JS, Park HT, Watanabe K, Inoue T, Kashiwagi M, Dairaku M, Tobari H, Hanada M. First neutral beam injection experiments on KSTAR tokamak. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:02B102. [PMID: 22380259 DOI: 10.1063/1.3660254] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D(+):D(2)(+):D(3)(+) = 75:20:5 at beam current density of 85 mA/cm(2). The arc efficiency is more than 1.0 A∕kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the T(i) and T(e) profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.
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Affiliation(s)
- S H Jeong
- Korea Atomic Energy Research Institute (KAERI), 989-111 Daedeokdaero, Yuseong-gu, Daejeon 305-353, South Korea.
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