ITB formation in terms of wExB flow shear and magnetic shear s on JET

Tuomas Tala, Jukka Heikkinen, V. Parail

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

A linear empirical threshold condition ωExBITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25% in Ti and Te profiles and 10-15% in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20%. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.
Original languageEnglish
Pages (from-to)507-523
Number of pages17
JournalPlasma Physics and Controlled Fusion
Volume43
Issue number4
Publication statusPublished - 2001
MoE publication typeA1 Journal article-refereed

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Shear flow
shear flow
shear
thresholds
Ions
Shearing
Flow velocity
Thermal gradients
Magnetic fields
ion temperature
profiles
shearing
Plasmas
Heating
temperature gradients
indication
simulation
flow velocity
heating
Experiments

Cite this

Tala, Tuomas ; Heikkinen, Jukka ; Parail, V. / ITB formation in terms of wExB flow shear and magnetic shear s on JET. In: Plasma Physics and Controlled Fusion. 2001 ; Vol. 43, No. 4. pp. 507-523.
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title = "ITB formation in terms of wExB flow shear and magnetic shear s on JET",
abstract = "A linear empirical threshold condition ωExB/γITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25{\%} in Ti and Te profiles and 10-15{\%} in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20{\%}. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.",
author = "Tuomas Tala and Jukka Heikkinen and V. Parail",
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journal = "Plasma Physics and Controlled Fusion",
issn = "0741-3335",
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ITB formation in terms of wExB flow shear and magnetic shear s on JET. / Tala, Tuomas; Heikkinen, Jukka; Parail, V.

In: Plasma Physics and Controlled Fusion, Vol. 43, No. 4, 2001, p. 507-523.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - ITB formation in terms of wExB flow shear and magnetic shear s on JET

AU - Tala, Tuomas

AU - Heikkinen, Jukka

AU - Parail, V.

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AB - A linear empirical threshold condition ωExB/γITG>0.68s-0.095 has been found for the onset of the ion internal transport barriers in the JET optimised shear database. Here, s is the magnetic shear, ωExB the flow shearing rate and γITG is an approximate of the linear growth rate of the ion temperature gradient instability. The present empirical threshold condition for the ITB formation will provide a first clear indication of the strong correlation of s and ωExB at the ITB transition. The empirical analysis consists of ITB discharges from a wide plasma parameter range; the toroidal magnetic field varies between 1.8-4.0 T, the auxiliary heating power between 10-30 MW and the diamagnetic energy between 3-12 MJ. The predictive simulations of several ITB discharges with the empirical ITB threshold condition reproduce the experiments with time averaged prediction errors of the order of 10-25% in Ti and Te profiles and 10-15% in ne profiles as well as the toroidal flow velocity with errors of the order of 10-20%. The simulated times of the onset of the ITB compared to the experimental ones are typically within 0.4 s and the simulated ITB widths within 0.1 in r/a throughout the whole simulations.

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