Millimeter-Wave Beam Scattering by Field-Aligned Blobs in Simple Magnetized Toroidal Plasmas

Chellaï, O.; Alberti, S.; Baquero-Ruiz, M.; Furno, I.; Goodman, T. P.; Manke, F.; Plyushchev, G.; Guidi, L.; Koehn, Alf; Maj, O.; Poli, E.; Hizanidis, Kyriakos; Figini, L.; Ricci, D.

doi:10.1103/physrevlett.120.105001

Cited by 29 publications

(33 citation statements)

References 40 publications

(50 reference statements)

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“…The tests also show that use of the OIMD allows distinguishing mmw detection variability due to plasma-related effects, an important prerequisite for experimental studies of propagation of mmws in turbulent plasmas. Indeed, recent measurements and results 8 show the usefulness of the system and its relevance for future research.…”

Section: Discussionmentioning

confidence: 93%

“…II) is set with B φ = 71 mT (on axis) and B z = 2 mT prior to starting the HWs. This leads to discharges exhibiting turbulence and intermittent structures that can scatter mmws 8 .…”

Section: Tests and Discussionmentioning

confidence: 99%

“…In plasma physics, mmws are widely used in diagnostic systems such as interferometers 5 as well as for plasma heating in fusiongrade tokamaks 6 . At present, there is significant interest in gaining understanding on the propagation of mmws in turbulent plasmas 7,8 , as it may have important implications in the deposition of heating power and current drive efficiency in fusion experiments 9 .…”

Section: Introductionmentioning

confidence: 99%

“…II). Noise in the SDD output signal reached an unacceptable level for experiments whose aim was to distinguish fluctuations in the detection of the ≈ 30 GHz mmw beam 8 .…”

Section: Introductionmentioning

confidence: 99%

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Optically isolated millimeter-wave detector for the Toroidal Plasma Experiment

Baquero-Ruiz

Alberti

Chellaï

et al. 2018

Review of Scientific Instruments

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We have designed and built an optically-isolated millimeter-wave detection system to prevent interference from a nearby, powerful, 2.45 GHz microwave source in millimeter-wave propagation experiments in the TORoroidal Plasma Experiment (TORPEX). A series of tests demonstrates excellent system noise immunity and the ability to observe effects that cannot be resolved in a setup using a bare Schottky diode detector.

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Section: Discussionmentioning

confidence: 93%

“…II) is set with B φ = 71 mT (on axis) and B z = 2 mT prior to starting the HWs. This leads to discharges exhibiting turbulence and intermittent structures that can scatter mmws 8 .…”

Section: Tests and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…II). Noise in the SDD output signal reached an unacceptable level for experiments whose aim was to distinguish fluctuations in the detection of the ≈ 30 GHz mmw beam 8 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optically isolated millimeter-wave detector for the Toroidal Plasma Experiment

Baquero-Ruiz

Alberti

Chellaï

et al. 2018

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

show abstract

“…In the 1980s high-power microwave sources became available and the interaction of injected microwaves and plasma edge density fluctuations in fusion-relevant scenarios was studied with geometrical-optics tools [14,15]. Due to the potentially negative consequences for NTM stabilization in ITER, this topic has gained significant traction since 2009 [16][17][18][19][20][21]. tion and the fluid equation of motion of the electrons on a 2D Cartesian grid.…”

Section: Introductionmentioning

confidence: 99%

The deteriorating effect of plasma density ﬂuctuations on microwave beam quality

et al. 2019

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Turbulent plasma edge density fluctuations can broaden a traversing microwave beam degrading its quality. This can be a problem for scenarios relying on a high spatial localization of the deposition of injected microwave power, like controlling MHD instabilities. Here we present numerical estimations of the scattering of a microwave beam by density fluctuations over a large parameter range, including extrapolations to ITER. Two codes are used, the full-wave code IPF-FDMC and the wave kinetic equation solver WKBeam. A successful comparison between beam broadening obtained from DIII-D experiments and corresponding fullwave simulations is shown. 2 Numerical tools 2.1 The full-wave code IPF-FDMC The full-wave code IPF-FDMC is based on the finitedifference time-domain scheme. It solves Maxwell's equa-arXiv:1805.09594v1 [physics.plasm-ph]

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Homogenization theory for the effective permittivity of a turbulent tokamak plasma in the scrape-off layer

et al. 2018

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There has been a growing interest, over the past few years, on understanding the effect on radio frequency waves due to turbulence in the scrape-off layer of tokamak plasmas. While the far scrape-off layer density width is of the order of centimetres in contemporary tokamaks, in ITER (International Thermonuclear Experimental Reactor), and in future fusion reactors, the corresponding width will be of the order of tens of centimetres. As such, this could impact the spectral properties of the waves and, consequently, the transport of wave energy and momentum to the core plasma. The turbulence in the scrape-off layer spans a broad range of spatial scales and includes blobs and filaments that are elongated along the magnetic field lines. The propagation of radio frequency waves through this tenuous plasma is given by Maxwell’s equations. The characteristic properties of the plasma appear as a permittivity tensor in the expression for the current in Ampere’s equation. This paper develops a formalism for expressing the permittivity of a turbulent plasma using the homogenization technique. This technique has been extensively used to express the dielectric properties of composite materials that are spatially inhomogeneous, for example, due to the presence of micro-structures. In a similar vein, the turbulent plasma in the scrape-off layer is spatially inhomogeneous and can be considered as a composite material in which the micro-structures are filaments and blobs. The classical homogenization technique is not appropriate for the magnetized plasma in the scrape-off layer, as the radio frequency waves span a broad range of wavelengths and frequencies – from tens of megahertz to hundreds of gigahertz. The formalism in this paper makes use of the Fourier space components of the electric and magnetic fields of the radio frequency waves for the scattered fields and fields inside the filaments and blobs. These are the eigenvectors of the dispersion matrix which, using the Green’s function approach, lead to a homogenized dielectric tensor.

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Millimeter-Wave Beam Scattering by Field-Aligned Blobs in Simple Magnetized Toroidal Plasmas

Cited by 29 publications

References 40 publications

Optically isolated millimeter-wave detector for the Toroidal Plasma Experiment

Optically isolated millimeter-wave detector for the Toroidal Plasma Experiment

The deteriorating effect of plasma density ﬂuctuations on microwave beam quality

Homogenization theory for the effective permittivity of a turbulent tokamak plasma in the scrape-off layer

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