### Abstract

Original language | English |
---|---|

Pages (from-to) | 475-491 |

Journal | Plasma Physics and Controlled Fusion |

Volume | 44 |

Issue number | 5 |

DOIs | |

Publication status | Published - 2002 |

MoE publication type | A1 Journal article-refereed |

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### Keywords

- Monte Carlo
- Monte Carlo simulation
- plasma
- fusion energy

### Cite this

*Plasma Physics and Controlled Fusion*,

*44*(5), 475-491. https://doi.org/10.1088/0741-3335/44/5/302

}

*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.

Research output: Contribution to journal › Article › Scientific › peer-review

TY - JOUR

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

Y1 - 2002

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

IS - 5

ER -