Synthetic NPA diagnostic for energetic particles in JET plasmas

J. Varje, P. Sirén, H. Weisen, T. Kurki-Suonio, S. Äkäslompolo, J. E.T. Contributors

    Research output: Contribution to journalArticleScientificpeer-review

    Abstract

    Neutral particle analysis (NPA) is one of the few methods for diagnosing fast ions inside a plasma by measuring neutral atom fluxes emitted due to charge exchange reactions. The JET tokamak features an NPA diagnostic which measures neutral atom fluxes and energy spectra simultaneously for hydrogen, deuterium and tritium species. A synthetic NPA diagnostic has been developed and used to interpret these measurements to diagnose energetic particles in JET plasmas with neutral beam injection (NBI) heating. The synthetic NPA diagnostic performs a Monte Carlo calculation of the neutral atom fluxes in a realistic geometry. The 4D fast ion distributions, representing NBI ions, were simulated using the Monte Carlo orbit-following code ASCOT. Neutral atom density profiles were calculated using the FRANTIC neutral code in the JINTRAC modelling suite. Additionally, for rapid analysis, a scan of neutral profiles was precalculated with FRANTIC for a range of typical plasma parameters. These were taken from the JETPEAK database, which includes a comprehensive set of data from the flat-top phases of nearly all discharges in recent JET campaigns. The synthetic diagnostic was applied to various JET plasmas in the recent hydrogen campaign where different hydrogen/deuterium mixtures and NBI configurations were used. The simulated neutral fluxes from the fast ion distributions were found to agree with the measured fluxes, reproducing the slowing-down profiles for different beam isotopes and energies and quantitatively estimating the fraction of hydrogen and deuterium fast ions.

    Original languageEnglish
    Article numberC11025
    JournalJournal of Instrumentation
    Volume12
    Issue number11
    DOIs
    Publication statusPublished - 22 Nov 2017
    MoE publication typeA1 Journal article-refereed
    Event2nd European Conference on Plasma Diagnostics, ECPD 2017 - Bordeaux, France
    Duration: 18 Apr 201721 Apr 2017

    Fingerprint

    neutral particles
    energetic particles
    neutral atoms
    Diagnostics
    Plasma
    beam injection
    Fluxes
    Plasmas
    neutral beams
    Deuterium
    Ions
    deuterium
    Atoms
    Hydrogen
    ion distribution
    hydrogen
    profiles
    ions
    Tritium
    tritium

    Keywords

    • Analysis and statistical methods
    • Nuclear instruments and methods for hot plasma diagnostics
    • Simulation methods and programs

    Cite this

    Varje, J., Sirén, P., Weisen, H., Kurki-Suonio, T., Äkäslompolo, S., & Contributors, J. E. T. (2017). Synthetic NPA diagnostic for energetic particles in JET plasmas. Journal of Instrumentation, 12(11), [C11025]. https://doi.org/10.1088/1748-0221/12/11/C11025
    Varje, J. ; Sirén, P. ; Weisen, H. ; Kurki-Suonio, T. ; Äkäslompolo, S. ; Contributors, J. E.T. / Synthetic NPA diagnostic for energetic particles in JET plasmas. In: Journal of Instrumentation. 2017 ; Vol. 12, No. 11.
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    abstract = "Neutral particle analysis (NPA) is one of the few methods for diagnosing fast ions inside a plasma by measuring neutral atom fluxes emitted due to charge exchange reactions. The JET tokamak features an NPA diagnostic which measures neutral atom fluxes and energy spectra simultaneously for hydrogen, deuterium and tritium species. A synthetic NPA diagnostic has been developed and used to interpret these measurements to diagnose energetic particles in JET plasmas with neutral beam injection (NBI) heating. The synthetic NPA diagnostic performs a Monte Carlo calculation of the neutral atom fluxes in a realistic geometry. The 4D fast ion distributions, representing NBI ions, were simulated using the Monte Carlo orbit-following code ASCOT. Neutral atom density profiles were calculated using the FRANTIC neutral code in the JINTRAC modelling suite. Additionally, for rapid analysis, a scan of neutral profiles was precalculated with FRANTIC for a range of typical plasma parameters. These were taken from the JETPEAK database, which includes a comprehensive set of data from the flat-top phases of nearly all discharges in recent JET campaigns. The synthetic diagnostic was applied to various JET plasmas in the recent hydrogen campaign where different hydrogen/deuterium mixtures and NBI configurations were used. The simulated neutral fluxes from the fast ion distributions were found to agree with the measured fluxes, reproducing the slowing-down profiles for different beam isotopes and energies and quantitatively estimating the fraction of hydrogen and deuterium fast ions.",
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    author = "J. Varje and P. Sir{\'e}n and H. Weisen and T. Kurki-Suonio and S. {\"A}k{\"a}slompolo and Contributors, {J. E.T.}",
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    Varje, J, Sirén, P, Weisen, H, Kurki-Suonio, T, Äkäslompolo, S & Contributors, JET 2017, 'Synthetic NPA diagnostic for energetic particles in JET plasmas', Journal of Instrumentation, vol. 12, no. 11, C11025. https://doi.org/10.1088/1748-0221/12/11/C11025

    Synthetic NPA diagnostic for energetic particles in JET plasmas. / Varje, J.; Sirén, P.; Weisen, H.; Kurki-Suonio, T.; Äkäslompolo, S.; Contributors, J. E.T.

    In: Journal of Instrumentation, Vol. 12, No. 11, C11025, 22.11.2017.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Synthetic NPA diagnostic for energetic particles in JET plasmas

    AU - Varje, J.

    AU - Sirén, P.

    AU - Weisen, H.

    AU - Kurki-Suonio, T.

    AU - Äkäslompolo, S.

    AU - Contributors, J. E.T.

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    AB - Neutral particle analysis (NPA) is one of the few methods for diagnosing fast ions inside a plasma by measuring neutral atom fluxes emitted due to charge exchange reactions. The JET tokamak features an NPA diagnostic which measures neutral atom fluxes and energy spectra simultaneously for hydrogen, deuterium and tritium species. A synthetic NPA diagnostic has been developed and used to interpret these measurements to diagnose energetic particles in JET plasmas with neutral beam injection (NBI) heating. The synthetic NPA diagnostic performs a Monte Carlo calculation of the neutral atom fluxes in a realistic geometry. The 4D fast ion distributions, representing NBI ions, were simulated using the Monte Carlo orbit-following code ASCOT. Neutral atom density profiles were calculated using the FRANTIC neutral code in the JINTRAC modelling suite. Additionally, for rapid analysis, a scan of neutral profiles was precalculated with FRANTIC for a range of typical plasma parameters. These were taken from the JETPEAK database, which includes a comprehensive set of data from the flat-top phases of nearly all discharges in recent JET campaigns. The synthetic diagnostic was applied to various JET plasmas in the recent hydrogen campaign where different hydrogen/deuterium mixtures and NBI configurations were used. The simulated neutral fluxes from the fast ion distributions were found to agree with the measured fluxes, reproducing the slowing-down profiles for different beam isotopes and energies and quantitatively estimating the fraction of hydrogen and deuterium fast ions.

    KW - Analysis and statistical methods

    KW - Nuclear instruments and methods for hot plasma diagnostics

    KW - Simulation methods and programs

    U2 - 10.1088/1748-0221/12/11/C11025

    DO - 10.1088/1748-0221/12/11/C11025

    M3 - Article

    AN - SCOPUS:85038576194

    VL - 12

    JO - Journal of Instrumentation

    JF - Journal of Instrumentation

    SN - 1748-0221

    IS - 11

    M1 - C11025

    ER -

    Varje J, Sirén P, Weisen H, Kurki-Suonio T, Äkäslompolo S, Contributors JET. Synthetic NPA diagnostic for energetic particles in JET plasmas. Journal of Instrumentation. 2017 Nov 22;12(11). C11025. https://doi.org/10.1088/1748-0221/12/11/C11025