Inference of <i>α</i>-particle density profiles from ITER collective Thomson scattering

Rasmussen, Jesper; Stejner, M.; Jensen, Thomas; Klinkby, E. B.; Korsholm, S. B.; Larsen, A.W.; Leipold, F.; Nielsen, S. K.; Salewski, M.

doi:10.1088/1741-4326/ab2f50

Cited by 11 publications

(15 citation statements)

References 52 publications

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“…Knowledge of the spatial and energy distribution of fusion-born alpha-particles in the magnetically confined plasma is required to assess the fusion performance and to further investigate the physics of fast ions at ITER [1,2]. For this purpose, a Collective Thomson Scattering (CTS) diagnostic is being designed [3].…”

Section: Introductionmentioning

confidence: 99%

Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Chambon¹,

Luís²,

Klinkby³

et al. 2021

J. Inst.

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The ITER Collective Thomson Scattering (CTS) system will be the main diagnostic responsible for measuring the velocity distribution function of fusion-born alpha particles in the plasma. As the CTS diagnostic is integrated in the equatorial port plug 12 (drawer 3), with direct apertures to the port interspace where maintenance hands-on operation will be carried out, it is essential to assess the shutdown dose rates (SDDR) in these maintenance areas. In this work, the D1S-UNED3.1.4 Monte-Carlo transport code, based on the implementation of the direct-one-step methodology in MCNP5 v1.60, was used to estimate the dose rate level 12 days (106 s) after shutdown in the port interspace. The results show that the CTS system does not contribute significantly to the SDDR in the area where hands-on maintenance is foreseen with contribution to dose rates less than 1 µSv/h. This is consistent with previous estimates, although with the most recent model of the CTS design there is a slight increase of the SDDR values. This deviation can be attributed to design changes and improved shielding modelling and/or most importantly, to statistical fluctuations of the D1S simulations. From a neutronics point of view, the increase in the SDDR falls within the range of the statistical fluctuations, and the design is still compliant with the radiation safety ALARA principle aiming at minimizing radiation doses, and there is no requirement for further design optimizations.

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Section: Introductionmentioning

confidence: 99%

Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Chambon¹,

Luís²,

Klinkby³

et al. 2021

J. Inst.

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“…This assumes the plasma profiles provided with the 2019 Baseline equilibrium illustrated in figure 1, which includes thermalized D, T, and 4 He, fusion-born fast alphas, and 'impurities' in the form of H and 3 He from D-D fusion as well as Ar and Xe from impurity seeding. Since no fast-ion distribution functions are included with the equilibrium, we assume the fusion alphas to follow a classical slowing-down distribution, isotropic in velocity space (see also [22]). For simplicity, H and 3 He are assumed to be thermalized at the bulk ion temperature.…”

Section: Plasma Scenario and Raytracingmentioning

confidence: 99%

Core ion measurements with collective Thomson scattering for DEMO burn control

Rasmussen,

Korsholm

2024

Nucl. Fusion

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DEMO burn control will require measurements of a range of plasma parameters, but the suite of feasible diagnostics for this purpose is limited. Here we assess the accuracy with which a collective Thomson scattering (CTS) diagnostic can provide key measurements for burn control in the planned European DEMO (EU-DEMO). This is based on estimated signal-to-noise ratios for a conceptual diagnostic design and trial fits to synthetic DEMO CTS spectra. We show that a diagnostic with a single probe- and receiver beam setup will be able to provide simultaneous measurements of core fusion alpha density and ion temperature to mean accuracies better than 5 and 10%, respectively, along with detecting intrinsic toroidal rotation velocities down to within ∼5 km s-1. Adding a second CTS receiver view furthermore enables inference of the core fuel-ion ratio, allowing discrimination between, e.g., a 50/50% and 55/45% D/T mixture, while also providing useful information on the thermalized He content. A DEMO CTS diagnostic would thus be able to monitor fusion alpha densities as well as anomalous transport of fast alphas and heat from the plasma core, quantify plasma rotation for confinement enhancement, and track the core isotope mix for optimum fusion performance. This versatility makes such a diagnostic a potentially valuable tool for real-time burn control on DEMO.

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“…ITER CTS diagnostic is described in reports and highlighted in a number of publications [27][28][29]37,38 . Here, it will suffice to summarize the spatial resolution and the fulfillment of the measurement requirements.…”

Section: Please Cite This Article As Doi:101063/50101867mentioning

confidence: 99%

“…Based on such trial fits to synthetic spectra, performed as described in Ref. 37, we find that the spatial density profile of alpha particles can, on average, be constrained to within ~10% and 15% at 100 ms time resolution for the ITER baseline and steady-state plasma scenarios, respectively. This applies to all receivers probing plasma locations, corresponding to alpha densities n α > 10 17 m -3 , as set forth in the measurement requirements.…”

Section: Please Cite This Article As Doi:101063/50101867mentioning

confidence: 99%

ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

Korsholm

Chambon

Gonçalves³

et al. 2022

Review of Scientific Instruments

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The ITER Collective Thomson scattering (CTS) diagnostic will measure the dynamics of fusion-born alpha particles in the burning ITER plasma by scattering a 1 MW 60 GHz gyrotron beam off fast-ion induced fluctuations in the plasma. The diagnostic will have seven measurement volumes across the ITER cross section and will resolve the alpha particle energies in the range from 300 keV to 3.5 MeV; importantly, the CTS diagnostic is the only diagnostic capable of measuring confined alpha particles for energies below ∼1.7 MeV and will also be sensitive to the other fast-ion populations. The temporal resolution is 100 ms, allowing the capture of dynamics on that timescale, and the typical spatial resolution is 10–50 cm. The development and design of the in-vessel and primary parts of the CTS diagnostic has been completed. This marks the beginning of a new phase of preparation to maximize the scientific benefit of the diagnostic, e.g., by investigating the capability to contribute to the determination of the fuel-ion ratio and the bulk ion temperature as well as integrating data analysis with other fast-ion and bulk-ion diagnostics.

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Inference of α-particle density profiles from ITER collective Thomson scattering

Cited by 11 publications

References 52 publications

Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Assessment of shutdown dose rates in the ITER Collective Thomson Scattering system and in equatorial port plug 12

Core ion measurements with collective Thomson scattering for DEMO burn control

ITER collective Thomson scattering—Preparing to diagnose fusion-born alpha particles (invited)

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