Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.

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Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation. / Leyland, Matthew John; Beurskens, Marc N.A.; Flanagan, Joanne Claire; Frassinetti, Lorenzo; Gibson, Kieran J.; Kempenaars, M.; Maslov, M.; Scannell, Rory; JET Contibutors, ; Terentyev, Dmitry.

In: Review of Scientific Instruments, Vol. 87, No. 1, 013507 , 01.01.2016, p. 1-13.

Research output: Contribution to journalArticle

Harvard

Leyland, MJ, Beurskens, MNA, Flanagan, JC, Frassinetti, L, Gibson, KJ, Kempenaars, M, Maslov, M, Scannell, R, JET Contibutors, & Terentyev, D 2016, 'Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.', Review of Scientific Instruments, vol. 87, no. 1, 013507 , pp. 1-13. https://doi.org/10.1063/1.4939855

APA

Leyland, M. J., Beurskens, M. N. A., Flanagan, J. C., Frassinetti, L., Gibson, K. J., Kempenaars, M., ... Terentyev, D. (2016). Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation. Review of Scientific Instruments, 87(1), 1-13. [013507 ]. https://doi.org/10.1063/1.4939855

Vancouver

Leyland MJ, Beurskens MNA, Flanagan JC, Frassinetti L, Gibson KJ, Kempenaars M et al. Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation. Review of Scientific Instruments. 2016 Jan 1;87(1):1-13. 013507 . https://doi.org/10.1063/1.4939855

Author

Leyland, Matthew John ; Beurskens, Marc N.A. ; Flanagan, Joanne Claire ; Frassinetti, Lorenzo ; Gibson, Kieran J. ; Kempenaars, M. ; Maslov, M. ; Scannell, Rory ; JET Contibutors, ; Terentyev, Dmitry. / Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation. In: Review of Scientific Instruments. 2016 ; Vol. 87, No. 1. pp. 1-13.

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@article{435b9b05f2414e669f6f691b26fa207f,
title = "Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.",
abstract = "The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.",
keywords = "JET, Transition, Pedestal",
author = "Leyland, {Matthew John} and Beurskens, {Marc N.A.} and Flanagan, {Joanne Claire} and Lorenzo Frassinetti and Gibson, {Kieran J.} and M. Kempenaars and M. Maslov and Rory Scannell and {JET Contibutors} and Dmitry Terentyev",
note = "Score=10",
year = "2016",
month = "1",
day = "1",
doi = "10.1063/1.4939855",
language = "English",
volume = "87",
pages = "1--13",
journal = "Review of Scientific Instruments",
issn = "0034-6748",
publisher = "AIP - American Institute of Physics",
number = "1",

}

RIS - Download

TY - JOUR

T1 - Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.

AU - Leyland, Matthew John

AU - Beurskens, Marc N.A.

AU - Flanagan, Joanne Claire

AU - Frassinetti, Lorenzo

AU - Gibson, Kieran J.

AU - Kempenaars, M.

AU - Maslov, M.

AU - Scannell, Rory

AU - JET Contibutors, null

AU - Terentyev, Dmitry

N1 - Score=10

PY - 2016/1/1

Y1 - 2016/1/1

N2 - The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.

AB - The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.

KW - JET

KW - Transition

KW - Pedestal

UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/35747796

U2 - 10.1063/1.4939855

DO - 10.1063/1.4939855

M3 - Article

VL - 87

SP - 1

EP - 13

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

SN - 0034-6748

IS - 1

M1 - 013507

ER -

ID: 5647833