Development of microwave imaging reflectometry in large helical device

Yamaguchi, Soichiro; Nagayama, Y.; Kuwahara, D.; Yoshinaga, T.; Shi, Z. B.; Kogi, Y.; Mase, A.

doi:10.1063/1.2993741

Cited by 10 publications

(10 citation statements)

References 8 publications

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“…A combined system of MIR and ECEI (electron cyclotron emission imaging) as shown in Fig. 1 has been applied to the Large Helical Device (LHD) [11][12][13]. The MIR system uses 4 different frequency sources in order to obtain the information at 4 radial positions.…”

Section: Microwave/millimeter-wave System With Quasi-optical Transmission Linementioning

confidence: 99%

Reflectometric measurement of plasma imaging and applications

et al. 2012

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Progress in microwave and millimeter-wave technologies has made possible advanced diagnostics for application to various fields, such as, plasma diagnostics, radio astronomy, alien substance detection, airborne and spaceborne imaging radars called as synthetic aperture radars, living body measurements. Transmission, reflection, scattering, and radiation processes of electromagnetic waves are utilized as diagnostic tools. In this report we focus on the reflectometric measurements and applications to biological signals (vital signal detection and breast cancer detection) as well as plasma diagnostics, specifically by use of imaging technique and ultra-wideband radar technique.

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Section: Microwave/millimeter-wave System With Quasi-optical Transmission Linementioning

confidence: 99%

Reflectometric measurement of plasma imaging and applications

et al. 2012

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“…With multiple detectors and multiple operating frequencies, MIR promises to provide a capability for diagnosis of spatially localized density fluctuations comparable to that realized by ECEI for temperature fluctuations. The MIR system on LHD [25][26][27] represents a groundbreaking achievement in 3D imaging of density fluctuations, and provides data key to understanding the transport properties of this stellarator device. At the heart of the LHD MIR system is a horn mixer array (HMA) which combines well-characterized pyramidial horn antennas, Schottky diode mixers, and IF amplification in a single shielded and expandable unit.…”

Section: Recent Advancements In Mirmentioning

confidence: 99%

Recent Progress on Microwave Imaging Technology and New Physics Results

Tobias

Luhmann

Domier

et al. 2011

Plasma and Fusion Research

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Techniques for visualizing turbulent flow in nature and in the laboratory have evolved over half a millennium from Leonardo da Vinci's sketches of cascading waterfalls to the advanced imaging technologies which are now pervasive in our daily lives. Advancements in millimeter wave imaging have served to usher in a new era in plasma diagnostics, characterized by ever improving 2D, and even 3D, images of complex phenomena in tokamak and stellarator plasmas. Examples at the forefront of this revolution are electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR). ECEI has proved to be a powerful tool as it has provided immediate physics results following successful diagnostic installations on TEXTOR, ASDEX-U, DIII-D, and KSTAR. Recent results from the MIR system on LHD are demonstrating that this technique has the potential for comparable impact in the diagnosis of electron density fluctuations. This has motivated a recent resurgence in MIR research and development, building on a prototype system demonstrated on TEXTOR, toward the realization of combined ECEI/MIR systems on DIII-D and KSTAR for simultaneous imaging of electron temperature and density fluctuations. The systems discussed raise the standard for fusion plasma diagnostics and present a powerful new capability for the validation of theoretical models and numerical simulations.

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“…the cutoff layer that may represent density fluctuation [3]. MIR has been intensively developed at the National Institute for Fusion Science (NIFS) for the TPE-RX RFP device [3,4] and for the large helical device (LHD) [5][6][7][8]. In the last MIR experiment at LHD [8], a newly developed horn-antenna millimeter-wave imaging detector (HMID) [9,10] was employed.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Electron Density Fluctuations Using O-Mode Microwave Imaging Reflectometry in a TST-2 Spherical Tokamak

Nagayama

Ejiri

Takase

et al. 2020

Plasma and Fusion Research

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An O-mode microwave imaging reflectometry system has been installed in a spherical tokamak named TST-2. The illumination wave frequency is 23 -32 GHz, which corresponds to the cutoff electron density of 0.65 -1.3 × 10 19 m −3 . The microwave image of the scattered wave is formed on an imaging detector named horn-antenna millimeter-wave imaging detector by imaging optics that consist of an ellipsoidal aluminum mirror, a Teflon lens, and a dielectric plate. The detected channel numbers are 6 (poloidal) × 6 (toroidal) × 2 (radial). The data of power and phase of the scattered wave are sampled every 0.5 µs and are stored by the LABCOM system at the National Institute for Fusion Science via a private network named SNET. The scattered wave quickly fluctuates (∼5 µs) and has a large amplitude (>100 times). From the time evolution of the phase at the internal reconnection event, it is inferred that the reduction in amplitude may be owing to the phase mixing of scattered wave in each detector channel.

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Development of microwave imaging reflectometry in large helical device

Cited by 10 publications

References 8 publications

Reflectometric measurement of plasma imaging and applications

Reflectometric measurement of plasma imaging and applications

Recent Progress on Microwave Imaging Technology and New Physics Results

Measurement of Electron Density Fluctuations Using O-Mode Microwave Imaging Reflectometry in a TST-2 Spherical Tokamak

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