A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER

Jaspers, Rje Roger; Scheffer, M.; Kappatou, A.; Valk, van der Ncj; Durkut, M.; Snijders, B.; Marchuk, O.; Biel, W.; Pokol, G. I.; Erdei, Gábor; Zoletnik, S.; Dunai, D.

doi:10.1063/1.4732058

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…The primary measurements of the CXRS are made by a three colour channel high-étendue spectrometer 20 which was originally designed as a prototype for ITER and previously used on the TEXTOR 21 and ASDEX-Upgrade 22 tokamaks. The spectrometer, known as the 'ITER-Like spectrometer' (ILS) has 54 fibres, each of which are split into three colour channels to ultimately provide all the primary measurements at the same 54 spatial locations.…”

Section: Spectrometersmentioning

confidence: 99%

Charge exchange recombination spectroscopy at Wendelstein 7-X

Ford

Vanó

Alonso

et al. 2020

Review of Scientific Instruments

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The Charge Exchange Recombination Spectroscopy (CXRS) diagnostic has become a routine diagnostic on almost all major high temperature fusion experimental devices. For the optimised stellarator W7-X, a highly flexible and extensive CXRS diagnostic has been built to provide high-resolution local measurements of several important plasma parameters using the recently commissioned neutral beam heating. This paper outlines the design specifics of the W7-X CXRS system and gives examples of the initial results obtained including typical ion temperature profiles for several common heating scenarios, toroidal flow and radial electric field derived from velocity measurements, beam attenuation via beam emission spectra and finally, normalised impurity density profiles under some typical plasma conditions.

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Section: Spectrometersmentioning

confidence: 99%

Charge exchange recombination spectroscopy at Wendelstein 7-X

Ford

Vanó

Alonso

et al. 2020

Review of Scientific Instruments

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“…The charge exchange measurements are performed on neutral beam injection (NBI) source #3, one of the four sources of NBI box I, which has a maximum acceleration voltage of 60 keV. Two different spectroscopic instruments are used: the boron measurements were performed with the spectrometer described in [10] and the helium measurements were performed with the system described in [11]. Both measurements extend from the plasma center to approximately ρ tor = 0.85.…”

Section: Database Of Helium and Boron Density Profilesmentioning

confidence: 99%

Understanding helium transport: experimental and theoretical investigations of low-Z impurity transport at ASDEX Upgrade

et al. 2019

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The presence of helium is fundamentally connected to the performance of a fusion reactor, as fusion-produced helium is expected to heat the plasma bulk, while He "ash" accumulation dilutes the fusion fuel. An understanding of helium transport via experimentally validated theoretical models of the low-Z impurity turbulent transport is indispensable to predict the helium density profile in future fusion devices. At ASDEX Upgrade, detailed, multi-species investigations of low-Z impurity transport have been undertaken in dedicated experiments, resulting in an extensive database of helium and boron density profiles over a wide range of parameters relevant for turbulent transport (normalised gradients of the electron density, the ion temperature, and the toroidal rotation profiles, the collisionality and the electron to ion temperature ratio). Helium is not found to accumulate in the parameter space investigated, as the shape of the helium density profile follows largely that of the electron density. Helium is observed to be as peaked as the electron density at high electron cyclotron resonance heating fraction, and less peaked than the electron density at high neutral beam heating fraction. The boron density profile is found to be consistently less peaked than the electron density profile. Detailed comparisons of the experimental density gradients of both impurities with quasilinear gyrokinetic simulations have shown that a qualitative agreement between experiment and theory cannot always be obtained, with strong discrepancies observed in some cases.

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“…The time traces of the most relevant plasma parameters during the discharge are shown in figure 4. In this discharge, the helium spectra were measured using the high étendue spectrometer described in [10]. The spectrometer was connected to two optical heads: one with predominantly toroidal LOS [17] and one with more poloidal LOS [13], both focussed on neutral beam source #3 (see figure 5).…”

Section: Derivation Of Helium Density Profiles Using Different Observmentioning

confidence: 99%

“…The helium content in the plasma is measured routinely at ASDEX Upgrade utilising a high étendue spectrometer designed for core charge exchange measurements in ITER [10]. This instrument measures three wavelength ranges simultaneously, namely the carbon, helium and D α (beam emission) spectra.…”

Section: Introductionmentioning

confidence: 99%

A forward model for the helium plume effect and the interpretation of helium charge exchange measurements at ASDEX Upgrade

Kappatou

McDermott

Pütterich

et al. 2018

Plasma Phys. Control. Fusion

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The analysis of the charge exchange measurements of helium is hindered by an additional emission contributing to the spectra, the helium 'plume' emission (Fonck et al 1984 Phys. Rev. A 29 3288), which complicates the interpretation of the measurements. The plume emission is indistinguishable from the active charge exchange signal when standard analysis of the spectra is applied and its intensity is of comparable magnitude for ASDEX Upgrade conditions, leading to a significant overestimation of the He 2+ densities if not properly treated. Furthermore, the spectral line shape of the plume emission is non-Gaussian and leads to wrong ion temperature and flow measurements when not taken into account. A kinetic model for the helium plume emission has been developed for ASDEX Upgrade. The model is benchmarked against experimental measurements and is shown to capture the underlying physics mechanisms of the plume effect, as it can reproduce the experimental spectra and provides consistent values for the ion temperature, plasma rotation, and He 2+ density.

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A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER

Cited by 11 publications

References 5 publications

Charge exchange recombination spectroscopy at Wendelstein 7-X

Charge exchange recombination spectroscopy at Wendelstein 7-X

Understanding helium transport: experimental and theoretical investigations of low-Z impurity transport at ASDEX Upgrade

A forward model for the helium plume effect and the interpretation of helium charge exchange measurements at ASDEX Upgrade

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