Experimental Measurement of ECH Deposition Broadening: Beyond Anomalous
Transport

Brookman, M. W.; Austin, M. E.; Gentle, K. W.; Petty, C. C.; Ernst, D.; Peysson, Y.; Decker, J.; Barada, K.

doi:10.1051/epjconf/201714703001

Cited by 15 publications

(18 citation statements)

References 18 publications

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“…In terms of the microwave plasma diagnostics the probing beam broadening results in deterioration of the spatial resolution and it may complicate the diagnostic data interpretation. Experimental conformation of the broadened ECRH deposition was observed for DIII-D tokamak [13]. The microwave power scattering off blobs and the edge turbulence was also experimentally examined on TORPEX [14,15] and TCV tokamak [16,17] correspondingly.…”

Section: Introductionmentioning

confidence: 99%

X-mode beam broadening in turbulent plasma

Tretinnikov¹,

Gusakov²,

Heuraux³

2021

Plasma Phys. Control. Fusion

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It is shown that plasma turbulence at the edge of a fusion machine can lead to significant broadening of an X-mode microwave beam, which also impacts the performance of the heating systems and diagnostics. Based on a similar method developed for O-mode polarization, the expression for the mean microwave power distribution after the beam passes through the plasma edge turbulence is obtained, and its spatial and probabilistic distributions are analyzed. As this polarization is used for collective Thomson scattering (CTS) on ITER and for electron cyclotron resonance heating (ECRH) on ASDEX Upgrade, numerical simulations of beam broadening due to the edge turbulence are performed for the two conditions of plasma parameters, related to the planned CTS experiments on ITER and to ECRH experiments on ASDEX Upgrade. Ideas to reduce the beam broadening induced by the edge turbulence in the CTS case have been tested and are summarized in the conclusion.

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Section: Introductionmentioning

confidence: 99%

X-mode beam broadening in turbulent plasma

Tretinnikov¹,

Gusakov²,

Heuraux³

2021

Plasma Phys. Control. Fusion

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“…The precise amount of EC-beam broadening may strongly depend on the characteristics of the turbulent structures [21] and could reach more than a factor of 2 [17], complicating the tearing mode stabilization in ITER [19,22] with the present EC plant design. Experimental measurements of mmw scattering by blobs in fusion plasmas are hampered by diagnostic accessibility and have been, to date, limited to attempts to compare indirectly inferred heating power deposition profiles with predictions of the ray-tracing code TORAY-GA [23]. Direct experimental evidence of scattering-and the induced broadening, which is of fundamental importance for the validation of codes and quantitative predictions-is still missing.…”

mentioning

confidence: 99%

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

et al. 2018

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The first direct experimental measurements of the scattering of a millimeter-wave beam by plasma blobs in a simple magnetized torus are reported. The wavelength of the beam is comparable to the characteristic size of the blob. In situ Langmuir probe measurements show that fluctuations of the electron density induce correlated fluctuations of the transmitted power. A first-principles full-wave model, using conditionally sampled 2D electron density profiles, predicts fluctuations of the millimeter-wave power that are in agreement with experiments.

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“…An accompanying transport analysis separates the effect of profile broadening due to diffusion and due to other effects like a turbulent edge layer. Broadening of the injected EC beam of up to a factor of 2.5 could be determined in DIII-D this way, as presented on the last EC-conference [39]. Inspired by these experiments, we elaborated the possibility of performing simulations resembling the experiment as closely as possible.…”

Section: Simulation-experiments Comparisonmentioning

confidence: 97%

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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Experimental Measurement of ECH Deposition Broadening: Beyond Anomalous Transport

Cited by 15 publications

References 18 publications

X-mode beam broadening in turbulent plasma

X-mode beam broadening in turbulent plasma

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

The deteriorating effect of plasma density ﬂuctuations on microwave beam quality

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