Determination of divertor stray light in high-resolution main chamber H<sub>α</sub> spectroscopy in JET-ILW

Neverov, V.S.; Kukushkin, A. B.; Stamp, M.; Alekseev, A. G.; Brezinsek, S.; Hellermann, M. von; Contributors, Jet

doi:10.1088/0029-5515/57/1/016031

Cited by 23 publications

(27 citation statements)

References 16 publications

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“…Isotope ratios were primarily based on line intensity ratios from high resolution Balmer-alpha spectroscopy, using a set of several vertical viewing lines passing through the divertor (Neverov et al 2017). Residual gas analysis in the sub-divertor, based on Penning gauge spectroscopy (Kruezi et al 2012) was also available.…”

Section: Diagnostics and Data Analysis For Jet-ilw Isotope Studiesmentioning

confidence: 99%

“…(for i = 1, 2) from 1 to 2 (King et al 2017(King et al , 2020. The isotope composition was inferred from the line intensity ratios of the Balmer-α lines of the two species, as measured from high resolution divertor spectroscopy (Neverov et al 2017). Below 10 MW, in pure hydrogen, a type I ELMy regime was not always achieved.…”

Section: Transport In Mixed Isotope Elmy H-modesmentioning

confidence: 99%

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Isotope dependence of energy, momentum and particle confinement in tokamaks

Weisen

Maggi²,

Oberparleiter³

et al. 2020

J. Plasma Phys.

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The isotope dependence of plasma transport will have a significant impact on the performance of future D-T experiments in JET and ITER and eventually on the fusion gain and economics of future reactors. In preparation for future D-T operation on JET, dedicated experiments and comprehensive transport analyses were performed in H, D and H-D mixed plasmas. The analysis of the data has demonstrated an unexpectedly strong and favourable dependence of the global confinement of energy, momentum and particles in ELMy H-mode plasmas on the atomic mass of the main ion species, the energy confinement time scaling as ${\tau _E}\sim {A^{0.5}}$ (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045; JET Team, Nucl. Fusion, vol. 39, 1999, pp. 1227–1244), i.e. opposite to the expectations based only on local gyro-Bohm (GB) scaling, ${\tau _E}\sim {A^{ - 0.5}}$ , and stronger than in the commonly used H-mode scaling for the energy confinement (Saibene et al., Nucl. Fusion, vol. 39, 1999, 1133; ITER Physics Basis, Nucl. Fusion, vol. 39, 1999, 2175). The scaling of momentum transport and particle confinement with isotope mass is very similar to that of energy transport. Nonlinear local GENE gyrokinetic analysis shows that the observed anti-GB heat flux is accounted for if collisions, E × B shear and plasma dilution with low-Z impurities (9Be) are included in the analysis (E and B are, respectively the electric and magnetic fields). For L-mode plasmas a weaker positive isotope scaling ${\tau _E}\sim {A^{0.14}}$ has been found in JET (Maggi et al., Plasma Phys. Control. Fusion, vol. 60, 2018, 014045), similar to ITER97-L scaling (Kaye et al., Nucl. Fusion, vol. 37, 1997, 1303). Flux-driven quasi-linear gyrofluid calculations using JETTO-TGLF in L-mode show that local GB scaling is not followed when stiff transport (as is generally the case for ion temperature gradient modes) is combined with an imposed boundary condition taken from the experiment, in this case predicting no isotope dependence. A dimensionless identity plasma pair in hydrogen and deuterium L-mode plasmas has demonstrated scale invariance, confirming that core transport physics is governed, as expected, by the 4 dimensionless parameters ρ*, ν*, β, q (normalised ion Larmor radius, collisionality, plasma pressure and safety factor) consistently with global quasi-linear gyrokinetic TGLF calculations (Maggi et al., Nucl. Fusion, vol. 59, 2019, 076028). We compare findings in JET with those in different devices and discuss the possible reasons for the different isotope scalings reported from different devices. The diversity of observations suggests that the differences may result not only from differences affecting the core, e.g. heating schemes, but are to a large part due to differences in device-specific edge and wall conditions, pointing to the importance of better understanding and controlling pedestal and edge processes.

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Section: Diagnostics and Data Analysis For Jet-ilw Isotope Studiesmentioning

confidence: 99%

Section: Transport In Mixed Isotope Elmy H-modesmentioning

confidence: 99%

Isotope dependence of energy, momentum and particle confinement in tokamaks

Weisen

Maggi²,

Oberparleiter³

et al. 2020

J. Plasma Phys.

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“…Applicability of a couple of different methods to avert the stray light has been investigated. From detailed spectrum shape analysis, because the divertor stray light and emission from the scrape off layer had different spectrum shape, the stray light from the divertor was successfully estimated, and the actual signal was deduced in JET ITER like wall arauthor's e-mail: kajita.shin@nagoya-u.jp rangement [7,8]. Transfer matrices prepared by ray tracing simulations were used to eliminate the stray light in synthetic ITER divertor emission [9,10].…”

Section: Introductionmentioning

confidence: 99%

Ray Trace Study for Visible Spectroscopy Reference System (VSRS) Diagnostics in ITER

Kajita

Bock²,

Desjardins³

et al. 2019

Plasma and Fusion Research

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The visible spectroscopy reference system (VSRS) diagnostic will be used to measure the continuum visible light emitted from the plasma in ITER. Because the field of view of the VSRS system is aligned to a hole on a blanket module with a retroreflector on the bottom, which will be shared with an interferometer measurement, it has a potential to be free from the stray light, which may disturb signals for optical diagnostics in ITER. In this study, performance of the stray light reduction in the VSRS is investigated using a ray tracing simulation. We investigated the influences of the reflection property of the retroreflector and first mirror for the signal and stray light intensity.

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“…this refer to References [7][8][9] or to a more recent reference [10], where the fitting is explicitly used to A more complex situation is presented in Figure 2 where a second neutral population with a…”

mentioning

confidence: 99%

Spectral Modeling of Hydrogen Radiation Emission in Magnetic Fusion Plasmas

Koubiti

Sheeba

2019

Atoms

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Modeling of the spectral line and continuum radiation emitted by hydrogen isotopes in peripheral regions of magnetic fusion is presented through profiles of the Zeeman-Doppler broadened Hα/Dα line and those of the Stark broadened high-n Balmer lines extending beyond the series limit for recombining plasmas. The Hα/Dα line profiles should be modelled while accounting for several populations of neutrals to mimic real situations and analyze experimental data for isotopic ratio determination. On the other side, high-n Balmer lines of hydrogen are used for plasma electron density and temperature diagnostics. Moreover, modelling whole spectra including the continuum radiation contributes to the development of synthetic diagnostics for future magnetic fusion devices for which they can give predictive results through coupling to numerical simulation tools.

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Determination of divertor stray light in high-resolution main chamber H_α spectroscopy in JET-ILW

Cited by 23 publications

References 16 publications

Isotope dependence of energy, momentum and particle confinement in tokamaks

Isotope dependence of energy, momentum and particle confinement in tokamaks

Ray Trace Study for Visible Spectroscopy Reference System (VSRS) Diagnostics in ITER

Spectral Modeling of Hydrogen Radiation Emission in Magnetic Fusion Plasmas

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Determination of divertor stray light in high-resolution main chamber Hα spectroscopy in JET-ILW

Cited by 23 publications

References 16 publications

Isotope dependence of energy, momentum and particle confinement in tokamaks

Isotope dependence of energy, momentum and particle confinement in tokamaks

Ray Trace Study for Visible Spectroscopy Reference System (VSRS) Diagnostics in ITER

Spectral Modeling of Hydrogen Radiation Emission in Magnetic Fusion Plasmas

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Determination of divertor stray light in high-resolution main chamber H_α spectroscopy in JET-ILW