Design of tangential viewing phase contrast imaging for turbulence measurements in JT-60SA

Tanaka, Kaoru; Coda, S.; Yoshida, M.; Sasao, H.; Kawano, Y.; Imazawa, Ryota; Kubo, H.; Kamada, Y.

doi:10.1063/1.4960057

Cited by 3 publications

(5 citation statements)

References 11 publications

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“…First of all, for a range of wavevector orientations there are two locations along the beam that satisfy the selection rule. These two locations (distinguished by the line type, solid versus dashed) are separated by a significant distance, of the order of 4 m. This effect (which was overlooked in [12], whose figure 4 is therefore partly incorrect) is due to the quadruple pass through the plasma. The split localization into two segments, featured for part of the measurement, adds some degree of complication.…”

Section: Spatial Localization Of the Measurementmentioning

confidence: 98%

“…This paper presents the basis for the design of a TPCI diagnostic for JT-60SA, following an earlier, preliminary proposal [12], to measure ion-and possibly electron-scale turbulence, as well as initial gyrokinetic modeling that confirms the appropriateness of the proposal. Section 2 briefly describes the PCI technique and the principles underlying the localization achieved by TPCI.…”

Section: Introductionmentioning

confidence: 96%

“…The proposed tangential PCI (TPCI) diagnostic for JT-60SA offers a unique opportunity to study turbulence for the first time in a reactor-grade device, in a variety of scenarios that should help answer critical questions for ITER and DEMO. This paper presents the basis for the design of a TPCI diagnostic for JT-60SA, following an earlier, preliminary proposal [12], to measure ion-and possibly electron-scale turbulence, as well as initial gyrokinetic modeling that confirms the appropriateness of the proposal. Section 2 briefly describes the PCI technique and the principles underlying the localization achieved by TPCI.…”

Section: Introductionmentioning

confidence: 96%

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A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

Coda¹,

Iantchenko²,

Brunner³

et al. 2021

Nucl. Fusion

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A core fluctuation diagnostic based on the phase-contrast imaging (PCI) technique has been designed for the JT-60SA tokamak, with the assistance of a synthetic diagnostic coupled to a gyrokinetic code. Using a tangentially viewing geometry, this system would be able to resolve small-scale microturbulence as well as macroscopic fluctuations, with good spatial and temporal resolution, throughout the plasma cross-section and in all plasma regimes. The spatial resolution will be optimal (<5% of the minor radius) in the pedestal region and near the magnetic axis. The accessible wave-number range will cover the main ion-scale instabilities predicted to be at play, and optionally also the electron-scale ones. The new superconducting tokamak JT-60SA, which is due to begin operating in 2021, will be the largest tokamak ever built and the most significant intermediate step in magnetic-confinement fusion before the inception of ITER operations. Turbulence is the primary cause of anomalous transport, one of the primary limiting factors in controlled nuclear fusion. Understanding and possibly controlling turbulence thus remain paramount to the fusion quest, and JT-60SA offers the possibility of performing such studies for the first time in a true reactor-relevant environment, providing also a unique opportunity for code validation. This proposal is supported by a direct modeling effort, employing the gyrokinetic code gene and a PCI synthetic diagnostic. Linear and nonlinear flux-tube simulations have been performed for a typical high-performance scenario, to identify the spectral and spatial areas of interest and illustrate the potential for fruitful theory-experiment comparison. While only electrostatic simulations could be carried to full completion with the computing resources deployed for this study, the work has highlighted the importance of including electromagnetic effects for proper comparisons.

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Section: Spatial Localization Of the Measurementmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 96%

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A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

Coda¹,

Iantchenko²,

Brunner³

et al. 2021

Nucl. Fusion

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“…On TCV, tangential injection was attempted and fine spatial resolution was obtained at around tangent location to the magnetic field [15,16]. The same concept was proposed for JT-60SA [17].…”

Section: Jinst 15 C01045mentioning

confidence: 99%

Determination of absolute turbulence amplitude by CO₂ laser phase contrast imaging

et al. 2020

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Phase contrast imaging (PCI) has the important advantages of good sensitivity and applicability for the measurements of fluctuation and turbulence in magnetically confined plasma. However, the determination of the absolute amplitude of fluctuation is not well established. In this article, we propose to determine the absolute amplitude of fluctuation with calibration. The fluctuation measured by CO 2 laser PCI (CO 2 -PCI) was confirmed by simultaneous measurements by using a HeNe heterodyne interferometer (HeNe-HI). In the test experiments, CO 2 -PCI and HeNe-HI measured sound fields, which are produced by the audio speaker ( f = 6 ∼ 18 kHz, k = 0.09 ∼ 0.33 mm −1 ) and the piezoelectric transducer ( f = 72 kHz, k = 1.3 mm −1 ). At f = 13 ∼ 18 kHz, k = 0.24 ∼ 0.33 mm −1 , the differences between CO 2 -PCI and HeNe-HI were 20 ∼ 30%. At f = 72 kHz, k = 1.3 mm −1 , the difference was less than ∼ 10%. On the other hand, the difference between PCI and HI becomes larger at f < 13 kHz, k < 0.24 mm −1 . This is because in these regions some parts of the scattered and non-scattered radiation were not clearly separated inside and outside the groove of the phase plate. The procedure of the absolute value determination was applied to the detached plasma of LHD and compared with the measurement by using a CO 2 laser heterodyne interferometer (CO 2 -HI). The signal of CO 2 -HI at f > 20 kHz is almost at the same as the level of noise. On the other hand, the 2D-PCI signal is clearly higher than the level 1Corresponding author.

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“…Another turbulence diagnostic that is actively studied is phase contrast imaging (PCI). A system is being designed using a tangential viewing implementation and spatial filtering based on magnetic shearing in order to obtain localized information on both electron and ion scale turbulence [34]. Using a 10.6 µm CO 2 laser and liquid nitrogen cooled detector, local turbulence measurements become possible.…”

Section: Beam Emission Spectroscopymentioning

confidence: 99%

Physics and operation oriented activities in preparation of the JT-60SA tokamak exploitation

et al. 2017

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The JT-60SA tokamak, being built under the Broader Approach agreement jointly by Europe and Japan, is due to start operation in 2020 and is expected to give substantial contributions to both ITER and DEMO scenario optimisation. A broad set of preparation activities for an efficient start of the experiments on JT-60SA is being carried out, involving elaboration of the Research Plan, advanced modelling in various domains, feasibility and conception studies of diagnostics and other sub-systems in connection with the priorities of the scientific programme, development and validation of operation tools. The logic and coherence of this approach, as well as the most significant results of the main activities undertaken are presented and summarised.

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Design of tangential viewing phase contrast imaging for turbulence measurements in JT-60SA

Cited by 3 publications

References 11 publications

A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

Determination of absolute turbulence amplitude by CO₂ laser phase contrast imaging

Physics and operation oriented activities in preparation of the JT-60SA tokamak exploitation

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Design of tangential viewing phase contrast imaging for turbulence measurements in JT-60SA

Cited by 3 publications

References 11 publications

A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

A phase-contrast-imaging core fluctuation diagnostic and first-principles turbulence modeling for JT-60SA

Determination of absolute turbulence amplitude by CO2 laser phase contrast imaging

Physics and operation oriented activities in preparation of the JT-60SA tokamak exploitation

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Determination of absolute turbulence amplitude by CO₂ laser phase contrast imaging