Parameterization of Balmer-alpha asymmetric line shape in tokamak SOL plasmas

Kukushkin, A. B.; Neverov, V.S.; Kadomtsev, M. B.; Kotov, V.; Kukushkin, A. S.; Levashova, M.G.; Lisgo, S.; Lisitsa, V. S.; Shurygin, V. A.; Alekseev, A. G.

doi:10.1088/1742-6596/548/1/012012

Cited by 11 publications

(22 citation statements)

References 7 publications

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“…Sometimes the experimental signal may be saturated on the core of the spectral line. Our algorithm would allow one to reconstruct the core of the line shape from the data for the wings of the line shape, however the first constraint in equation (11) in [10] is violated in this case. In this work we do not interpret the data with the saturated signal.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Note that, in [10], the following models are used: (a) the (normalized) spectral line shape (not absolute values of spectral intensity!) of the DSL is described with the model [4]; (b) the spectral line shape asymmetry of the intensity of the emission in the SOL, caused by the non-Maxwellian effects (the net inward flux of relatively fast atoms), is described with the model [11]; and (c) the recovery of main parameters of a non-Maxwellian VDF of neutral hydrogen atoms in the SOL (namely, effective temperatures of Maxwellian and non-Maxwellian fractions and the relative content of the hydrogen isotopes) is carried out using the model [12]. The model [12] in its turn relies on the results of the Ballistic Model [13,14] for the VDF (in the projection of velocity on the direction normal to the chamber wall and the coordinate along this direction) of the hydrogen neutrals in the SOL.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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Section: Theoretical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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“…парциальных вкладов каждого из изотопов водорода в смеси, так как в последней не требуется определять абсолютные концентрации атомов дейтерия и трития, а лишь разделять потоки фотонов в линиях D и T (впрочем, в силу близости этих спектральных линий достижение требуемой точности измерений оказывается серьёзной проблемой). Поэтому при решении второй задачи можно было использовать параметрическую модель контура линии [4,5], не использующую информацию о плотностях и температурах электронов и ионов в СОЛ. Однако для измерения потока атомов знание профилей плотности и температуры плазмы в СОЛ уже необходимо.…”

Section: постановка задачиunclassified

Analysis of Accuracy of Measuring the Flux Density of All Hydrogen Isotopes From First Wall to Plasma Using the H-Alpha Diagnostics in Iter

Kukushkin¹,

Neverov²,

Lisitsa³

et al. 2019

PAST-TF

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В статье представлены результаты анализа точности измерения плотности потока всех изотопов водорода с первой стенки основной вакуумной камеры в плазму токамака ИТЭР с помощью спектроскопии высокого разрешения линий бальмер-альфа изотопов водорода (Н-альфа-диагностика). В условиях ожидаемого высокого фонового излучения, создаваемого рассеянным диверторным светом, и отсутствия возможности использования оптических ловушек в ИТЭР необходима дифференциальная схема измерения, использующая пространственную вариацию коэффициента отражения света от естественного ландшафта первой стенки. Анализ точности измерения проведён с помощью метода синтетической диагностики, использующего результаты предсказательного численного моделирования различных режимов рециклинга водорода для расчёта ожидаемых диагностических сигналов и определения искомых параметров путём решения обратной задачи.Ключевые слова: спектроскопия высокого разрешения, линии бальмер-альфа, изотопы водорода, Н-альфа-диагностика, токамак, ИТЭР.The results of the analysis of the accuracy of measuring the flux density of all hydrogen isotopes from the first wall of the main vacuum chamber to the ITER tokamak plasma using the high-resolution spectroscopy of Balmer-alpha lines of hydrogen isotopes (H-alpha diagnostics) are presented. Under the conditions of the expected high background radiation generated by the divertor stray light and the absence of the possibility of using the optical dumps in ITER, a differential measurement scheme is necessary, which uses the spatial variation of the coefficient of the light reflection from the natural landscape of the first wall. The measurement accuracy analysis is carried out with the help of the method of synthetic diagnostics, which uses the results of the predictive numerical modeling of different modes of hydrogen recycling for simulation of the expected diagnostic signals and determination of the sought-for parameters by solving an inverse problem. ВВЕДЕНИЕПроведение анализа, представленного в настоящей статье, мотивировано недавним отказом от использования оптических ловушек в основной камере ИТЭР для интерпретации измерений диагностики «Спектроскопия водородных линий» (называемой в международной версии Hα-диагностикой, 55.E2 H-alpha (+Visible) Spectroscopy Diagnostic), поставляемой Россией в ИТЭР. Как показали исследования возможности стабилизации оптической системы в условиях её механических движений во время разря-(0) (0) (0) 2. J J J  На рис. 4 показаны результаты наилучшей подгонки синтетических спектров линии Dα в сценариях «d» и «o» для одного из тысячи расчётов в каждом случае. Несовпадение штриховых и сплошных кривых отражает зависимость результата решения обратной задачи от характера профилей плазмы в СОЛ и ошибки их измерения.

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“…The interpretation is more straightforward for the divertor chords compared to the midplane radial and tangential chords due to the σ-component blocking and the absence of significant stray light. We defined the neutral VDF model to be composed of: a single non-Maxwellian component with statistical weight S N M , temperature T N M and the damping parameter Λ which quantifies the attenuation of the inward flux (see [14] for details); two Maxwellian components parametrised together with the statistical weights S M1 , S M2 and corresponding temperatures T M1 and T M2 . Figure 10 shows an example of the weighted fit for pulse 86959 at t =9.65 s and R =2.52 m with parameter estimates and standard errors.…”

Section: Simulation Setupmentioning

confidence: 99%

Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

et al. 2015

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract.A parametrised spectral line profile model is formulated to investigate the diagnostic scope for recovering plasma parameters from hydrogenic Balmer and Paschen series spectroscopy in the context of JET-ILW divertor plasmas. The separate treatment of Zeeman and Stark contributions in the line model is tested against the PPP-B code which accounts for their combined influence on the spectral line shape. The proposed simplified model does not fully reproduce the Stark-Zeeman features for the α and β transitions, but good agreement is observed in the line width and wing profiles, especially for n >5. The line model has been applied to infer radial density profiles in the JET-ILW divertor with generally good agreement between the D 5→2, 5→3, 6→2, 7→2 and 9→2 lines for high recycling and detached conditions. In an L-mode detached plasma pulse the Langmuir probe measurements typically underestimated the density by a factor 2-3 and overestimated the electron temperature by a factor of 5-10 compared to spectroscopically derived values. The line model is further used to generate synthetic high-resolution spectra for low-n transitions to assess the potential for parameter recovery using a multi-parametric fitting technique. In cases with 4 parameter fits with a single Maxwellian neutral temperature component the D 4→3 line yields the best results with parameter estimates within 10% of the input values. For cases with 9 parameter fits inclusive of a multi-component neutral velocity distribution function the quality of the fits is degraded. Simultaneous fitting of the D 3→2 and 4→3 profiles improves the fit quality significantly, highlighting the importance of complementary spectroscopic measurements for divertor plasma emission studies.

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Parameterization of Balmer-alpha asymmetric line shape in tokamak SOL plasmas

Cited by 11 publications

References 7 publications

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

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

Analysis of Accuracy of Measuring the Flux Density of All Hydrogen Isotopes From First Wall to Plasma Using the H-Alpha Diagnostics in Iter

Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

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Parameterization of Balmer-alpha asymmetric line shape in tokamak SOL plasmas

Cited by 11 publications

References 7 publications

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

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

Analysis of Accuracy of Measuring the Flux Density of All Hydrogen Isotopes From First Wall to Plasma Using the H-Alpha Diagnostics in Iter

Inferring divertor plasma properties from hydrogen Balmer and Paschen series spectroscopy in JET-ILW

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

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