Monte Carlo simulations of central ion temperature measurements using neutral particle analysers

T. Kurki-Suonio (Corresponding Author), S. Sipilä, Jukka Heikkinen, H.-U. Fahrbach, A. Khudoleev, ASDEX Upgrade Team

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

A detailed Monte Carlo-based numerical analysis of ASDEX Upgrade discharges is presented, examining the applicability of neutral particle analysers (NPAs) for measuring the central ion temperature from the neutral particle spectra above the neutral beam injection energy. The analysis is motivated by an earlier work carried out for TFTR (Fiore C L et al 1988 Nucl. Fusion 28 1315), where the beams were quite tangential. This work is now extended to investigate the applicability of the method when the beams are perpendicular. The Monte Carlo simulations take fully into account the effects due to finite orbits and realistic magnetic geometry, and reveal that the fast ion distribution above the beam energy, generated by collisions, reflects the background temperature with good accuracy. However, it is found that the use of NPA tends to give temperature values that are up to 30% lower than the on-axis temperature Ti(0) assumed for the background. This is because the neutral fluxes measured by NPA originate from a wide radial region, and thus the measured spectrum is a chord-averaged one. A fairly tangential viewing is found to be optimal because in that case the signal originating from the centre of the plasma is enhanced relative to the signal from outer radii. It is concluded that, in discharges where the slowing down from electrons does not dominate the beam ion dynamics, NPA can give a reliable estimate of an average central temperature, Ti( = 0,...,0.3).
Original languageEnglish
Pages (from-to)475-491
JournalPlasma Physics and Controlled Fusion
Volume44
Issue number5
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

neutral particles
ion temperature
Temperature measurement
temperature measurement
Ions
simulation
Temperature
temperature
beam injection
ion distribution
neutral beams
Ion beams
numerical analysis
Numerical analysis
Orbits
Fusion reactions
fusion
ion beams
Monte Carlo simulation
Fluxes

Keywords

  • Monte Carlo
  • Monte Carlo simulation
  • plasma
  • fusion energy

Cite this

Kurki-Suonio, T., Sipilä, S., Heikkinen, J., Fahrbach, H-U., Khudoleev, A., & Team, ASDEX. U. (2002). Monte Carlo simulations of central ion temperature measurements using neutral particle analysers. Plasma Physics and Controlled Fusion, 44(5), 475-491. https://doi.org/10.1088/0741-3335/44/5/302
Kurki-Suonio, T. ; Sipilä, S. ; Heikkinen, Jukka ; Fahrbach, H.-U. ; Khudoleev, A. ; Team, ASDEX Upgrade. / Monte Carlo simulations of central ion temperature measurements using neutral particle analysers. In: Plasma Physics and Controlled Fusion. 2002 ; Vol. 44, No. 5. pp. 475-491.
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abstract = "A detailed Monte Carlo-based numerical analysis of ASDEX Upgrade discharges is presented, examining the applicability of neutral particle analysers (NPAs) for measuring the central ion temperature from the neutral particle spectra above the neutral beam injection energy. The analysis is motivated by an earlier work carried out for TFTR (Fiore C L et al 1988 Nucl. Fusion 28 1315), where the beams were quite tangential. This work is now extended to investigate the applicability of the method when the beams are perpendicular. The Monte Carlo simulations take fully into account the effects due to finite orbits and realistic magnetic geometry, and reveal that the fast ion distribution above the beam energy, generated by collisions, reflects the background temperature with good accuracy. However, it is found that the use of NPA tends to give temperature values that are up to 30{\%} lower than the on-axis temperature Ti(0) assumed for the background. This is because the neutral fluxes measured by NPA originate from a wide radial region, and thus the measured spectrum is a chord-averaged one. A fairly tangential viewing is found to be optimal because in that case the signal originating from the centre of the plasma is enhanced relative to the signal from outer radii. It is concluded that, in discharges where the slowing down from electrons does not dominate the beam ion dynamics, NPA can give a reliable estimate of an average central temperature, Ti( = 0,...,0.3).",
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Kurki-Suonio, T, Sipilä, S, Heikkinen, J, Fahrbach, H-U, Khudoleev, A & Team, ASDEXU 2002, 'Monte Carlo simulations of central ion temperature measurements using neutral particle analysers', Plasma Physics and Controlled Fusion, vol. 44, no. 5, pp. 475-491. https://doi.org/10.1088/0741-3335/44/5/302

Monte Carlo simulations of central ion temperature measurements using neutral particle analysers. / Kurki-Suonio, T. (Corresponding Author); Sipilä, S.; Heikkinen, Jukka; Fahrbach, H.-U.; Khudoleev, A.; Team, ASDEX Upgrade.

In: Plasma Physics and Controlled Fusion, Vol. 44, No. 5, 2002, p. 475-491.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Monte Carlo simulations of central ion temperature measurements using neutral particle analysers

AU - Kurki-Suonio, T.

AU - Sipilä, S.

AU - Heikkinen, Jukka

AU - Fahrbach, H.-U.

AU - Khudoleev, A.

AU - Team, ASDEX Upgrade

PY - 2002

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N2 - A detailed Monte Carlo-based numerical analysis of ASDEX Upgrade discharges is presented, examining the applicability of neutral particle analysers (NPAs) for measuring the central ion temperature from the neutral particle spectra above the neutral beam injection energy. The analysis is motivated by an earlier work carried out for TFTR (Fiore C L et al 1988 Nucl. Fusion 28 1315), where the beams were quite tangential. This work is now extended to investigate the applicability of the method when the beams are perpendicular. The Monte Carlo simulations take fully into account the effects due to finite orbits and realistic magnetic geometry, and reveal that the fast ion distribution above the beam energy, generated by collisions, reflects the background temperature with good accuracy. However, it is found that the use of NPA tends to give temperature values that are up to 30% lower than the on-axis temperature Ti(0) assumed for the background. This is because the neutral fluxes measured by NPA originate from a wide radial region, and thus the measured spectrum is a chord-averaged one. A fairly tangential viewing is found to be optimal because in that case the signal originating from the centre of the plasma is enhanced relative to the signal from outer radii. It is concluded that, in discharges where the slowing down from electrons does not dominate the beam ion dynamics, NPA can give a reliable estimate of an average central temperature, Ti( = 0,...,0.3).

AB - A detailed Monte Carlo-based numerical analysis of ASDEX Upgrade discharges is presented, examining the applicability of neutral particle analysers (NPAs) for measuring the central ion temperature from the neutral particle spectra above the neutral beam injection energy. The analysis is motivated by an earlier work carried out for TFTR (Fiore C L et al 1988 Nucl. Fusion 28 1315), where the beams were quite tangential. This work is now extended to investigate the applicability of the method when the beams are perpendicular. The Monte Carlo simulations take fully into account the effects due to finite orbits and realistic magnetic geometry, and reveal that the fast ion distribution above the beam energy, generated by collisions, reflects the background temperature with good accuracy. However, it is found that the use of NPA tends to give temperature values that are up to 30% lower than the on-axis temperature Ti(0) assumed for the background. This is because the neutral fluxes measured by NPA originate from a wide radial region, and thus the measured spectrum is a chord-averaged one. A fairly tangential viewing is found to be optimal because in that case the signal originating from the centre of the plasma is enhanced relative to the signal from outer radii. It is concluded that, in discharges where the slowing down from electrons does not dominate the beam ion dynamics, NPA can give a reliable estimate of an average central temperature, Ti( = 0,...,0.3).

KW - Monte Carlo

KW - Monte Carlo simulation

KW - plasma

KW - fusion energy

U2 - 10.1088/0741-3335/44/5/302

DO - 10.1088/0741-3335/44/5/302

M3 - Article

VL - 44

SP - 475

EP - 491

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

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ER -