Density peaking in JET—determined by fuelling or transport?

JET Contributers, T. Tala*, H. Nordman, A. Salmi, C. Bourdelle, J. Citrin, A. Czarnecka, F. Eriksson, E. Fransson, C. Giroud, J. Hillesheim, C. Maggi, P. Mantica, A. Mariani, M. Maslov, L. Meneses, S. Menmuir, S. Mordijck, Volker Naulin, M. Oberparleiter & 4 others G. Sips, D. Tegnered, M. Tsalas, H. Weisen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Core density profile peaking and electron particle transport have been extensively studied by performing several dimensionless collisionality (υ*) scans with other matched dimensionless profiles in various plasma operation scenarios on the Joint European Torus (JET). This is the first time when electron particle transport coefficients in the H-mode have been measured on JET with high resolution diagnostics, and therefore we are in a position to distinguish between the neutral beam injection (NBI) source and inward electron particle pinch in contributing to core density peaking. The NBI particle source is found to contribute typically 50%–60% to the electron density peaking in JET H-mode plasmas where Te/Ti ~ 1 or smaller and at υ*  =  0.1–0.5 (averaged between r/a  =  0.3–0.8), and being independent of υ* within that range. In these H-mode plasmas, the electron particle transport coefficients, De and ve, are small, thus giving rise to the large influence of NBI fueling with respect to transport effect on peaking. In L-mode plasma conditions, the role of the NBI source is small, typically 10%–20%, and the electron particle transport coefficients are large. These dimensionless υ* scans give the best possible data for model validation. TGLF simulations are in good agreement with the experimental results with respect to the role of NBI particle source versus inward pinch in affecting density peaking, both for the H-mode and L-mode υ* scans. It predicts, similarly to experimental results, that typically about half of the peaking originates from the NBI fuelling in the H-mode and 10%–20% in the L-mode. GENE simulation results also support the key role of NBI fuelling in causing a peaked density profile in JET H-mode plasma (Te/Ti ~ 1 and υ*  =  0.1–0.5) and, in fact, give an even higher weight on NBI fuelling than that experimentally observed or predicted by TGLF. For the non-fuelled H-mode plasma at higher Te/Ti  =  1.5 and lower βN and υ*, both TGLF and GENE predict peaked density profiles, therefore agreeing well with experimental steady-state density peaking. Overall, the various modelling results give a fairly good confidence in using TGLF and GENE in predicting density peaking in quite a wide range of plasma conditions in JET.
Original languageEnglish
Article number126030
JournalNuclear Fusion
Volume59
Issue number12
Number of pages16
ISSN0029-5515
DOIs
Publication statusPublished - 2019

Keywords

  • Density parking
  • Particle transport
  • NBI fuelling
  • Transport modelling
  • Particle pinch

Cite this

JET Contributers, Tala, T., Nordman, H., Salmi, A., Bourdelle, C., Citrin, J., ... Weisen, H. (2019). Density peaking in JET—determined by fuelling or transport? Nuclear Fusion, 59(12), [126030 ]. https://doi.org/10.1088/1741-4326/ab4248
JET Contributers ; Tala, T. ; Nordman, H. ; Salmi, A. ; Bourdelle, C. ; Citrin, J. ; Czarnecka, A. ; Eriksson, F. ; Fransson, E. ; Giroud, C. ; Hillesheim, J. ; Maggi, C. ; Mantica, P. ; Mariani, A. ; Maslov, M. ; Meneses, L. ; Menmuir, S. ; Mordijck, S. ; Naulin, Volker ; Oberparleiter, M. ; Sips, G. ; Tegnered, D. ; Tsalas, M. ; Weisen, H. / Density peaking in JET—determined by fuelling or transport?. In: Nuclear Fusion. 2019 ; Vol. 59, No. 12.
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title = "Density peaking in JET—determined by fuelling or transport?",
abstract = "Core density profile peaking and electron particle transport have been extensively studied by performing several dimensionless collisionality (υ*) scans with other matched dimensionless profiles in various plasma operation scenarios on the Joint European Torus (JET). This is the first time when electron particle transport coefficients in the H-mode have been measured on JET with high resolution diagnostics, and therefore we are in a position to distinguish between the neutral beam injection (NBI) source and inward electron particle pinch in contributing to core density peaking. The NBI particle source is found to contribute typically 50{\%}–60{\%} to the electron density peaking in JET H-mode plasmas where Te/Ti ~ 1 or smaller and at υ*  =  0.1–0.5 (averaged between r/a  =  0.3–0.8), and being independent of υ* within that range. In these H-mode plasmas, the electron particle transport coefficients, De and ve, are small, thus giving rise to the large influence of NBI fueling with respect to transport effect on peaking. In L-mode plasma conditions, the role of the NBI source is small, typically 10{\%}–20{\%}, and the electron particle transport coefficients are large. These dimensionless υ* scans give the best possible data for model validation. TGLF simulations are in good agreement with the experimental results with respect to the role of NBI particle source versus inward pinch in affecting density peaking, both for the H-mode and L-mode υ* scans. It predicts, similarly to experimental results, that typically about half of the peaking originates from the NBI fuelling in the H-mode and 10{\%}–20{\%} in the L-mode. GENE simulation results also support the key role of NBI fuelling in causing a peaked density profile in JET H-mode plasma (Te/Ti ~ 1 and υ*  =  0.1–0.5) and, in fact, give an even higher weight on NBI fuelling than that experimentally observed or predicted by TGLF. For the non-fuelled H-mode plasma at higher Te/Ti  =  1.5 and lower βN and υ*, both TGLF and GENE predict peaked density profiles, therefore agreeing well with experimental steady-state density peaking. Overall, the various modelling results give a fairly good confidence in using TGLF and GENE in predicting density peaking in quite a wide range of plasma conditions in JET.",
keywords = "Density parking, Particle transport, NBI fuelling, Transport modelling, Particle pinch",
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year = "2019",
doi = "10.1088/1741-4326/ab4248",
language = "English",
volume = "59",
journal = "Nuclear Fusion",
issn = "0029-5515",
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JET Contributers, Tala, T, Nordman, H, Salmi, A, Bourdelle, C, Citrin, J, Czarnecka, A, Eriksson, F, Fransson, E, Giroud, C, Hillesheim, J, Maggi, C, Mantica, P, Mariani, A, Maslov, M, Meneses, L, Menmuir, S, Mordijck, S, Naulin, V, Oberparleiter, M, Sips, G, Tegnered, D, Tsalas, M & Weisen, H 2019, 'Density peaking in JET—determined by fuelling or transport?', Nuclear Fusion, vol. 59, no. 12, 126030 . https://doi.org/10.1088/1741-4326/ab4248

Density peaking in JET—determined by fuelling or transport? / JET Contributers; Tala, T.; Nordman, H.; Salmi, A.; Bourdelle, C.; Citrin, J.; Czarnecka, A.; Eriksson, F.; Fransson, E.; Giroud, C.; Hillesheim, J.; Maggi, C.; Mantica, P.; Mariani, A.; Maslov, M.; Meneses, L.; Menmuir, S.; Mordijck, S.; Naulin, Volker; Oberparleiter, M.; Sips, G.; Tegnered, D.; Tsalas, M.; Weisen, H.

In: Nuclear Fusion, Vol. 59, No. 12, 126030 , 2019.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Density peaking in JET—determined by fuelling or transport?

AU - JET Contributers

AU - Tala, T.

AU - Nordman, H.

AU - Salmi, A.

AU - Bourdelle, C.

AU - Citrin, J.

AU - Czarnecka, A.

AU - Eriksson, F.

AU - Fransson, E.

AU - Giroud, C.

AU - Hillesheim, J.

AU - Maggi, C.

AU - Mantica, P.

AU - Mariani, A.

AU - Maslov, M.

AU - Meneses, L.

AU - Menmuir, S.

AU - Mordijck, S.

AU - Naulin, Volker

AU - Oberparleiter, M.

AU - Sips, G.

AU - Tegnered, D.

AU - Tsalas, M.

AU - Weisen, H.

PY - 2019

Y1 - 2019

N2 - Core density profile peaking and electron particle transport have been extensively studied by performing several dimensionless collisionality (υ*) scans with other matched dimensionless profiles in various plasma operation scenarios on the Joint European Torus (JET). This is the first time when electron particle transport coefficients in the H-mode have been measured on JET with high resolution diagnostics, and therefore we are in a position to distinguish between the neutral beam injection (NBI) source and inward electron particle pinch in contributing to core density peaking. The NBI particle source is found to contribute typically 50%–60% to the electron density peaking in JET H-mode plasmas where Te/Ti ~ 1 or smaller and at υ*  =  0.1–0.5 (averaged between r/a  =  0.3–0.8), and being independent of υ* within that range. In these H-mode plasmas, the electron particle transport coefficients, De and ve, are small, thus giving rise to the large influence of NBI fueling with respect to transport effect on peaking. In L-mode plasma conditions, the role of the NBI source is small, typically 10%–20%, and the electron particle transport coefficients are large. These dimensionless υ* scans give the best possible data for model validation. TGLF simulations are in good agreement with the experimental results with respect to the role of NBI particle source versus inward pinch in affecting density peaking, both for the H-mode and L-mode υ* scans. It predicts, similarly to experimental results, that typically about half of the peaking originates from the NBI fuelling in the H-mode and 10%–20% in the L-mode. GENE simulation results also support the key role of NBI fuelling in causing a peaked density profile in JET H-mode plasma (Te/Ti ~ 1 and υ*  =  0.1–0.5) and, in fact, give an even higher weight on NBI fuelling than that experimentally observed or predicted by TGLF. For the non-fuelled H-mode plasma at higher Te/Ti  =  1.5 and lower βN and υ*, both TGLF and GENE predict peaked density profiles, therefore agreeing well with experimental steady-state density peaking. Overall, the various modelling results give a fairly good confidence in using TGLF and GENE in predicting density peaking in quite a wide range of plasma conditions in JET.

AB - Core density profile peaking and electron particle transport have been extensively studied by performing several dimensionless collisionality (υ*) scans with other matched dimensionless profiles in various plasma operation scenarios on the Joint European Torus (JET). This is the first time when electron particle transport coefficients in the H-mode have been measured on JET with high resolution diagnostics, and therefore we are in a position to distinguish between the neutral beam injection (NBI) source and inward electron particle pinch in contributing to core density peaking. The NBI particle source is found to contribute typically 50%–60% to the electron density peaking in JET H-mode plasmas where Te/Ti ~ 1 or smaller and at υ*  =  0.1–0.5 (averaged between r/a  =  0.3–0.8), and being independent of υ* within that range. In these H-mode plasmas, the electron particle transport coefficients, De and ve, are small, thus giving rise to the large influence of NBI fueling with respect to transport effect on peaking. In L-mode plasma conditions, the role of the NBI source is small, typically 10%–20%, and the electron particle transport coefficients are large. These dimensionless υ* scans give the best possible data for model validation. TGLF simulations are in good agreement with the experimental results with respect to the role of NBI particle source versus inward pinch in affecting density peaking, both for the H-mode and L-mode υ* scans. It predicts, similarly to experimental results, that typically about half of the peaking originates from the NBI fuelling in the H-mode and 10%–20% in the L-mode. GENE simulation results also support the key role of NBI fuelling in causing a peaked density profile in JET H-mode plasma (Te/Ti ~ 1 and υ*  =  0.1–0.5) and, in fact, give an even higher weight on NBI fuelling than that experimentally observed or predicted by TGLF. For the non-fuelled H-mode plasma at higher Te/Ti  =  1.5 and lower βN and υ*, both TGLF and GENE predict peaked density profiles, therefore agreeing well with experimental steady-state density peaking. Overall, the various modelling results give a fairly good confidence in using TGLF and GENE in predicting density peaking in quite a wide range of plasma conditions in JET.

KW - Density parking

KW - Particle transport

KW - NBI fuelling

KW - Transport modelling

KW - Particle pinch

U2 - 10.1088/1741-4326/ab4248

DO - 10.1088/1741-4326/ab4248

M3 - Journal article

VL - 59

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 12

M1 - 126030

ER -

JET Contributers, Tala T, Nordman H, Salmi A, Bourdelle C, Citrin J et al. Density peaking in JET—determined by fuelling or transport? Nuclear Fusion. 2019;59(12). 126030 . https://doi.org/10.1088/1741-4326/ab4248