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

J. Rasmussen*, M. Stejner, T. Jensen, Esben Bryndt Klinkby, Søren Bang Korsholm, A.W. Larsen, Frank Leipold, S.K. Nielsen, Mirko Salewski

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born -particles. Based on the present design of the diagnostic, we compute and fit synthetic CTS spectra for the ITER baseline plasma scenario, including the effects of noise, refraction, multiple fast-ion populations, and uncertainties on nuisance parameters. As part of this, we developed a model for CTS that incorporates spatial effects of frequency-dependent refraction. While such effects will distort the measured ITER CTS spectra, we demonstrate that the true -particle densities can nevertheless be recovered to within  ∼10% from noisy synthetic spectra, using existing fitting methods that do not take these spatial effects into account. Under realistic operating conditions, we thus find the predicted performance of the ITER CTS system to be consistent with the ITER measurement requirements of a 20% accuracy on inferred -particle density profiles at 100 ms time resolution.
Original languageEnglish
Article number096051
JournalNuclear Fusion
Volume59
Issue number9
Number of pages17
ISSN0029-5515
DOIs
Publication statusPublished - 2019

Keywords

  • ITER
  • α-particles
  • Collective Thomson scattering

Cite this

@article{596b42e07ce048b086cb1354e4eb8aaf,
title = "Inference of α-particle density profiles from ITER collective Thomson scattering",
abstract = "The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born -particles. Based on the present design of the diagnostic, we compute and fit synthetic CTS spectra for the ITER baseline plasma scenario, including the effects of noise, refraction, multiple fast-ion populations, and uncertainties on nuisance parameters. As part of this, we developed a model for CTS that incorporates spatial effects of frequency-dependent refraction. While such effects will distort the measured ITER CTS spectra, we demonstrate that the true -particle densities can nevertheless be recovered to within  ∼10{\%} from noisy synthetic spectra, using existing fitting methods that do not take these spatial effects into account. Under realistic operating conditions, we thus find the predicted performance of the ITER CTS system to be consistent with the ITER measurement requirements of a 20{\%} accuracy on inferred -particle density profiles at 100 ms time resolution.",
keywords = "ITER, α-particles, Collective Thomson scattering",
author = "J. Rasmussen and M. Stejner and T. Jensen and Klinkby, {Esben Bryndt} and Korsholm, {S{\o}ren Bang} and A.W. Larsen and Frank Leipold and S.K. Nielsen and Mirko Salewski",
year = "2019",
doi = "10.1088/1741-4326/ab2f50",
language = "English",
volume = "59",
journal = "Nuclear Fusion",
issn = "0029-5515",
publisher = "IOP Publishing",
number = "9",

}

Inference of α-particle density profiles from ITER collective Thomson scattering. / Rasmussen, J.; Stejner, M.; Jensen, T.; Klinkby, Esben Bryndt; Korsholm, Søren Bang; Larsen, A.W.; Leipold, Frank; Nielsen, S.K.; Salewski, Mirko.

In: Nuclear Fusion, Vol. 59, No. 9, 096051, 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Inference of α-particle density profiles from ITER collective Thomson scattering

AU - Rasmussen, J.

AU - Stejner, M.

AU - Jensen, T.

AU - Klinkby, Esben Bryndt

AU - Korsholm, Søren Bang

AU - Larsen, A.W.

AU - Leipold, Frank

AU - Nielsen, S.K.

AU - Salewski, Mirko

PY - 2019

Y1 - 2019

N2 - The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born -particles. Based on the present design of the diagnostic, we compute and fit synthetic CTS spectra for the ITER baseline plasma scenario, including the effects of noise, refraction, multiple fast-ion populations, and uncertainties on nuisance parameters. As part of this, we developed a model for CTS that incorporates spatial effects of frequency-dependent refraction. While such effects will distort the measured ITER CTS spectra, we demonstrate that the true -particle densities can nevertheless be recovered to within  ∼10% from noisy synthetic spectra, using existing fitting methods that do not take these spatial effects into account. Under realistic operating conditions, we thus find the predicted performance of the ITER CTS system to be consistent with the ITER measurement requirements of a 20% accuracy on inferred -particle density profiles at 100 ms time resolution.

AB - The primary purpose of the collective Thomson scattering (CTS) diagnostic at ITER is to measure the properties of fast-ion populations, in particular those of fusion-born -particles. Based on the present design of the diagnostic, we compute and fit synthetic CTS spectra for the ITER baseline plasma scenario, including the effects of noise, refraction, multiple fast-ion populations, and uncertainties on nuisance parameters. As part of this, we developed a model for CTS that incorporates spatial effects of frequency-dependent refraction. While such effects will distort the measured ITER CTS spectra, we demonstrate that the true -particle densities can nevertheless be recovered to within  ∼10% from noisy synthetic spectra, using existing fitting methods that do not take these spatial effects into account. Under realistic operating conditions, we thus find the predicted performance of the ITER CTS system to be consistent with the ITER measurement requirements of a 20% accuracy on inferred -particle density profiles at 100 ms time resolution.

KW - ITER

KW - α-particles

KW - Collective Thomson scattering

U2 - 10.1088/1741-4326/ab2f50

DO - 10.1088/1741-4326/ab2f50

M3 - Journal article

VL - 59

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 9

M1 - 096051

ER -