Simultaneous microwave imaging system for density and temperature fluctuation measurements on TEXTOR (invited)

Park, H.; Mazzucato, E.; Munsat, T.; Domier, Calvin; Johnson, Michael H.; Luhmann, Neville C.; Wang, J.; Xia, Z. G.; Classen, I. G. J.; Donné, A. J. H.; Pol, M. J. van de

doi:10.1063/1.1794864

Cited by 79 publications

(31 citation statements)

References 18 publications

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“…One example of passive emission is electron cyclotron emission (ECE) in radiometry [5]; ECEs in fundamental and second harmonics have been used for electron temperature profile measurement. In recent years, owing to advances in microwave technology and data processing, 2D/3D imaging systems [6] that leverage ECE have been developed to generate new and detailed physics information regarding magnetohydrodynamic (MHD) instabilities and turbulence. In active diagnostics [5], both reflectometry (for electron density profiles and their fluctuations) and collective scattering systems have also provided momentum-resolved electron density fluctuations in Fourier (wave number and frequency) space.…”

Section: Role Of Radio Frequency and Microwaves In Magnetic Fusion Plmentioning

confidence: 99%

“…The novel character of ECE as a blackbody has been widely used to measure the local electron temperature, where the intensity of ECE is proportional to the electron temperature in the plasmas and the frequency corresponds to the local magnetic field [5]. The advancement of detection array technology and signal processing may enable the development of an imaging system used to visualize MHDs and turbulence [6].…”

Section: Application Of Radio Frequencies and Microwaves In Tokamentioning

confidence: 99%

“…The first 2D ECEI system [6] was tested on TEXTOR plasma, and was used to study the physics of a sawtooth crash (Fig. 5).…”

Section: Examples Of Microwave Diagnostics For Plasma Dynamics and Prmentioning

confidence: 99%

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Role of Radio Frequency and Microwaves in Magnetic Fusion Plasma Research

Park

2017

J Electromagn Eng Sci

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The role of electromagnetic (EM) waves in magnetic fusion plasma-ranging from radio frequency (RF) to microwaves-has been extremely important, and understanding of EM wave propagation and related technology in this field has significantly advanced magnetic fusion plasma research. Auxiliary heating and current drive systems, aided by various forms of high-power RF and microwave sources, have contributed to achieving the required steady-state operation of plasmas with high temperatures (i.e., up to approximately 10 keV; 1 eV = 10000 K) that are suitable for future fusion reactors. Here, various resonance values and cut-off characteristics of wave propagation in plasmas with a nonuniform magnetic field are used to optimize the efficiency of heating and current drive systems. In diagnostic applications, passive emissions and active sources in this frequency range are used to measure plasma parameters and dynamics; in particular, measurements of electron cyclotron emissions (ECEs) provide profile information regarding electron temperature. Recent developments in state-of-the-art 2D microwave imaging systems that measure fluctuations in electron temperature and density are largely based on ECE. The scattering process, phase delays, reflection/diffraction, and the polarization of actively launched EM waves provide us with the physics of magnetohydrodynamic instabilities and transport physics. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

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Section: Role Of Radio Frequency and Microwaves In Magnetic Fusion Plmentioning

confidence: 99%

Section: Application Of Radio Frequencies and Microwaves In Tokamentioning

confidence: 99%

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Role of Radio Frequency and Microwaves in Magnetic Fusion Plasma Research

Park

2017

J Electromagn Eng Sci

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“…Recent studies have used the frequency selective surface as protection notch filters in millimeter-wave imaging sensor systems for plasma diagnostics, i.e., electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry (MIR) [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Design of a 170 GHz Notch Filter for the KSTAR ECE Imaging Sensor Application

Mohyuddin¹,

Woo²,

Kim³

et al. 2016

Journal of Sensor Science and Technology

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A planar, light-weight, and low-cost notch filter structure is required for the KSTAR ECEI (Electron Cyclotron Emission Imaging) system to protect the mixer arrays from spurious plasma heating power. Without protection, this heating power can significantly degrade or damage the performance of the mixer array. To protect mixer arrays, a frequency selective surface (FSS) structure is the suitable choice as a notch filter to reject the spurious heating power. The FSS notch filter should be located between the lenses of the ECEI system. This paper presents a 170 GHz FSS notch filter for the KSTAR ECEI sensor application. The design of such an FSS notch filter is based on the single-sided square loop geometry, because that makes it relatively insensitive to the incident angle of incoming wave. The FSS notch filter exhibits high notch rejection with low pass-band insertion loss over a wide range of incident angles. This paper also reviews the simulated and measured results. The proposed FSS notch filter might be implemented in other millimeter-wave plasma devices.

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“…The prototype TEXTOR MIR system [2] based on reflective optics was moved to POSTECH in 2009 and has been tested in the laboratory [3]. The study of the MIR system was focused on designing a new MIR system for the 2012 KSTAR campaign, and the optics was intensively studied.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the imaging properties of Microwave Imaging Reflectometry

Hong¹,

Lee²,

Leem³

et al. 2012

J. Inst.

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Microwave Imaging Reflectometry (MIR) has been developed for unambiguous measurement of electron density fluctuations in fusion plasmas. The loss of phase information limiting the use of conventional reflectometry can be minimized by a large aperture imaging optics and an array of detectors in the MIR embodiment. The evaluation of the optical system is critical for precise reconstruction of the fluctuations. The optical systems of the prototype TEXTOR MIR [2] and newly-designed KSTAR MIR [5] systems have been tested with a corrugated target simulating density fluctuations at the cut-off surface. The reconstructed phase from the MIR system has been compared to the directly measured phase of corrugations taking into account the rotational speed of the target. The effects of optical aberrations and interference between lenses on the phase reconstruction have been investigated by the 2D amplitude measurement of the reflected waves and the diffraction-based optical simulations. (CODE V) A preliminary design of the KSTAR MIR optics has been suggested which can minimize the aberration and interference effects.

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Simultaneous microwave imaging system for density and temperature fluctuation measurements on TEXTOR (invited)

Cited by 79 publications

References 18 publications

Role of Radio Frequency and Microwaves in Magnetic Fusion Plasma Research

Role of Radio Frequency and Microwaves in Magnetic Fusion Plasma Research

Design of a 170 GHz Notch Filter for the KSTAR ECE Imaging Sensor Application

Evaluation of the imaging properties of Microwave Imaging Reflectometry

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