Noise suppression for MHD characterization with electron cyclotron emission imaging 1D technique

Yu, Guangyang; Kramer, G. J.; Zhu, Yilun; Li, Xiaoliang; Wang, Yingchu; Diallo, A.; Ren, Y.; Yu, Jian‐Shen; Chen, Ying; Liu, Xianzi; Cao, Jianyu; Zhao, Bingzhe; Austin, M. E.; Luhmann, Neville C.

doi:10.1088/1361-6587/abe9f2

Cited by 6 publications

(2 citation statements)

References 57 publications

(64 reference statements)

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“…In this paper, synthetic modeling [17,18] of the ECE radiation is applied to interpret the ECEI measurements of EHO and QCM. ECEI is a powerful imaging diagnostic technique [19][20][21] that can characterize the temperature fluctuations of core MHD, such as sawteeth [22,23], tearing modes [24][25][26] and Alfven eigenmodes [27][28][29][30][31]. The method is also applied to image the nonlinear fluctuation behavior associated with ELMs [32,33] and edge turbulence [34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

ECEI characterization of pedestal fluctuations in quiescent H-mode plasmas in DIII-D

Nazikian²,

Zhu³

et al. 2022

Plasma Phys. Control. Fusion

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Electron cyclotron emission imaging (ECEI) is employed to characterize the magneto hydraulics dynamics (MHD) fluctuations at the quiescent H-mode pedestals in DIII-D. Pedestal MHD fluctuations cause ECE radiation temperature fluctuations δ T e ,rad in both the pedestal and scrape-off-layer (SOL). A synthetic ECE platform is utilized for detailed interpretation of the ECEI signals in the SOL and pedestal regions. It is observed that the ECE radiation δ T e ,rad , which is located in the SOL region according to the cold and optically thick plasma resonance assumption, is extremely sensitive to MHD radial displacements near the separatrix, exhibiting radiation inversion to δ T e ,rad at the pedestal. Here, the radiation inversion refers to the opposite phase between the radiation fluctuation at the pedestal and the radiation fluctuation at the SOL. Consequently, the quasi-coherent MHD (QCM), which displays a radiation inversion, is found to be consistent with an MHD radial structure that has a strong displacement near the separatrix. In contrast, the edge harmonic oscillation (EHO), which displays weak or no inversion, is found to be consistent with an MHD radial displacement structure peaking at the pedestal top. The ECEI data, interpreted with synthetic ECE, are in qualitative agreement with beam emission spectroscopy measurements on DIII-D for the relative radial extent and localization of the EHO and QCM. The high sensitivity of ECE radiation to separatrix displacements can be used to detect turbulence or MHD fluctuations near the separatrix, which may affect the transport across the separatrix and the wetted area in the divertor. The δ T e ,rad inversion measured with an ECE or ECEI system potentially provides important information on the magnetic field B sep at the separatrix, which helps constrain the pedestal equilibrium reconstruction and achieve an unambiguous mapping of the ECE/ECEI system with respect to the separatrix.

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Section: Introductionmentioning

confidence: 99%

ECEI characterization of pedestal fluctuations in quiescent H-mode plasmas in DIII-D

Nazikian²,

Zhu³

et al. 2022

Plasma Phys. Control. Fusion

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“…The MMIC based V-band MIR system will be applied to replace the previous quasi-optical MIR approach [6] for electron density fluctuation imaging. The current W-band ECEI system operating on DIII-D, with 75-110 GHz working frequency, provides excellent temperature fluctuation results for the physics studies on the pedestal and low field side core region, including Alfven eigenmode, turbulence around magnetic islands, pedestal turbulence during ELM suppression, and pedestal MHD perturbations [10][11][12]. The F-band chip for ECEI instruments, which has a higher frequency extending from 110 GHz to 140 GHz, has been presented in this paper and will be applied on DIII-D for high field side temperature fluctuation measurement in late 2021.…”

Section: Introductionmentioning

confidence: 99%

System-on-chip integrated circuit technology applications on the DIII-D tokamak for multi-field measurements

Zheng

Chen

et al. 2022

J. Inst.

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Several mm-wave diagnostics on the DIII-D tokamak provide multi-scale and multi-dimensional measurements of plasma profile evolution and turbulence fluctuations. Mm-wave fusion plasma diagnostics that adopt system-on-chip integrated circuit technology can provide better space utilization, flexible installation, and improved sensitivity. In order to further extend this technology for additional fusion facilities with a higher toroidal magnetic field, V-band (55–75 GHz) and F-band (90–140 GHz) chips for Microwave Imaging Reflectometer (MIR) and Electron Cyclotron Emission Imaging (ECEI) instruments are developed and tested in the Davis Millimeter Wave Research Center (DMRC). Current measurement data show that correlation between these SoC-based diagnostic instruments with other state-of-the-art diagnostics enables co-located multi-field turbulence fluctuation measurement.

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System-on-chip approach microwave imaging reflectometer on DIII-D tokamak

Zhu

Chen

et al. 2022

Review of Scientific Instruments

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System-on-chip millimeter wave integrated circuit technology is used on the two-dimensional millimeter-wave imaging reflectometer (MIR) upgrade for density fluctuation imaging on the DIII-D tokamak fusion plasma. Customized CMOS chips have been successfully developed for the transmitter module and receiver module array, covering the 55–75 GHz working band. The transmitter module has the capability of simultaneously launching eight tunable probe frequencies (>0 dBm output power each). The receiver enclosure contains 12 receiver modules in two vertical lines. The quasi-optical local oscillator coupling of previous MIR systems has been replaced with an internal active frequency multiplier chain for improved local oscillator power delivery and flexible installation in a narrow space together with improved shielding against electromagnetic interference. The 55–75 GHz low noise amplifier, used between the receiver antenna and the first-stage mixer, significantly improves module sensitivity and suppresses electronics noise. The receiver module has a 20 dB gain improvement compared with the mini-lens approach and better than −75 dBm sensitivity, and its electronics noise temperature has been reduced from 55 000 K down to 11 200 K. The V-band MIR system is developed for co-located multi-field investigation of MHD-scale fluctuations in the pedestal region with W-band electron cyclotron emission imaging on DIII-D tokamak.

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Noise suppression for MHD characterization with electron cyclotron emission imaging 1D technique

Cited by 6 publications

References 57 publications

ECEI characterization of pedestal fluctuations in quiescent H-mode plasmas in DIII-D

ECEI characterization of pedestal fluctuations in quiescent H-mode plasmas in DIII-D

System-on-chip integrated circuit technology applications on the DIII-D tokamak for multi-field measurements

System-on-chip approach microwave imaging reflectometer on DIII-D tokamak

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