Design and development of the ITER CTS diagnostic

Korsholm, S. B.; Gonçalves, B.; Gutierrez, H.E.; Henriques, Elsa; Infante, V.; Jensen, Thomas; Jessen, M.; Klinkby, E. B.; Larsen, A.W.; Leipold, F.; Lopes, A.; Luís, R.; Naulin, V.; Nielsen, S. K.; Nonbøl, Erik; Rasmussen, Jesper; Salewski, M.; Stejner, M.; Taormina, A.; Vale, Alberto; Vidal, Catarina; Sánchez, Laura; Ballester, R. Morón; Udintsev, V. S.

doi:10.1051/epjconf/201920303002

Cited by 18 publications

(14 citation statements)

References 9 publications

(8 reference statements)

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“…The development and design of the ITER CTS diagnostic has been requirement driven; aiming at fulfilling the measurement requirements to the extent possible while balancing against the many technical, engineering, and operational requirements 32 . These requirements are increasing in importance and complexity when designing diagnostic systems for a burning plasma device as ITER, and can hardly be compared to the requirements of present devices.…”

Section: Overview Of the Diagnostic Designmentioning

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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Section: Overview Of the Diagnostic Designmentioning

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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show abstract

“…Collective Thomson scattering (CTS) has been proposed as a primary diagnostic for the measurement of fusionborn alpha particles (E a < 3:5 MeV). 1,2 It relies on scattering of an intense gyrotron beam at mm-wavelength (1 MW, 60 GHz) by fluctuations in the plasma, which are captured by receiver mirrors. The fast ions' velocity distribution is inferred from the measured spectrum.…”

Section: Introductionmentioning

confidence: 99%

Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic

et al. 2021

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For the measurement of the dynamics of fusion-born alpha particles E a 3:5 MeV in ITER using collective Thomson scattering (CTS), safe transmission of a gyrotron beam at mm-wavelength (1 MW, 60 GHz) passing the electron cyclotron resonance (ECR) in the in-vessel tokamak "port plug" vacuum is a prerequisite. Depending on neutral gas pressure and composition, ECR-assisted gas breakdown may occur at the location of the resonance, which must be mitigated for diagnostic performance and safety reasons. The concept of a split electrically biased waveguide (SBWG) has been previously demonstrated in C.P. Moeller, U.S. patent 4, 687,616 (1987). The waveguide is longitudinally split and a kV bias voltage is applied between the two halves. Electrons are rapidly removed from the central region of high radio frequency electric field strength, mitigating breakdown. As a full scale experimental investigation of gas and electromagnetic field conditions inside the ITER equatorial port plugs is currently unattainable, a corresponding Monte Carlo simulation study is presented. Validity of the Monte Carlo electron model is demonstrated with a prediction of ECR breakdown and the mitigation pressure limits for the above-quoted reference case with 1 H 2 (and pollutant high Z elements). For the proposed ITER CTS design with a 88.9 mm inner diameter SBWG, ECR breakdown is predicted to occur down to a pure 1 H 2 pressure of 0.3 Pa, while mitigation is shown to be effective at least up to 10 Pa using a bias voltage of 1 kV. The analysis is complemented by results for relevant electric/magnetic field arrangements and limitations of the SBWG mitigation concept are addressed.

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“…Collective Thomson scattering (CTS) has been proposed as a primary diagnostic for the measurement of fusion-born alpha particles (E α < 3.5 MeV). 1,2 It relies on scattering of an intense gyrotron beam at mm-wavelength (1 MW, 60 GHz) by fluctuations in the plasma, which are captured by receiver mirrors. The fast ions' velocity distribution is inferred from the measured spectrum.…”

Section: Introductionmentioning

confidence: 99%

Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic

Trieschmann,

Larsen,

Mussenbrock

et al. 2021

Preprint

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Design and development of the ITER CTS diagnostic

Cited by 18 publications

References 9 publications

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

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

Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic

Kinetic simulation of electron cyclotron resonance assisted gas breakdown in split-biased waveguides for ITER collective Thomson scattering diagnostic

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