Improved confinement in JET hybrid discharges

J. Hobirk; F. Imbeaux; F. Crisanti; P. Buratti; C.D. Challis; E. Joffrin; B. Alper; Y. Andrew; P. Beaumont; M. Beurskens; A. Boboc; A. Botrugno; M. Brix; G. Calabrò; I. Coffey; S. Conroy; O. Ford; D. Frigione; Joan Garcia; C. Giroud; N.C. Hawkes; D. Howell; I. Jenkins; D. Keeling; M. Kempenaars; H. Leggate; P. Lotte; E. De La Luna; G.P. Maddison; P. Mantica; C. Mazzotta; D.C. McDonald; A. Meigs; I. Nunes; E. Rachlew; F. Rimini; M. Schneider; A.C.C. Sips; J.K. Stober; W. Studholme; Tuomas Tala; M. Tsalas; I. Voitsekhovitch; P.C. de Vries; JET-EFDA contributors

doi:10.1088/0741-3335/54/9/095001

Improved confinement in JET hybrid discharges

J. Hobirk, F. Imbeaux, F. Crisanti, P. Buratti, C.D. Challis, E. Joffrin, B. Alper, Y. Andrew, P. Beaumont, M. Beurskens, A. Boboc, A. Botrugno, M. Brix, G. Calabrò, I. Coffey, S. Conroy, O. Ford, D. Frigione, Joan Garcia, C. GiroudN.C. Hawkes, D. Howell, I. Jenkins, D. Keeling, M. Kempenaars, H. Leggate, P. Lotte, E. De La Luna, G.P. Maddison, P. Mantica, C. Mazzotta, D.C. McDonald, A. Meigs, I. Nunes, E. Rachlew, F. Rimini, M. Schneider, A.C.C. Sips, J.K. Stober, W. Studholme, Tuomas Tala, M. Tsalas, I. Voitsekhovitch, P.C. de Vries, JET-EFDA contributors

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Abstract

A new technique has been developed to produce plasmas with improved confinement relative to the H_98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H_98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H_98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

Original language	English
Article number	095001
Journal	Plasma Physics and Controlled Fusion
Volume	54
Issue number	9
DOIs	https://doi.org/10.1088/0741-3335/54/9/095001
Publication status	Published - 2012
MoE publication type	A1 Journal article-refereed

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10.1088/0741-3335/54/9/095001

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Hobirk, J., Imbeaux, F., Crisanti, F., Buratti, P., Challis, C. D., Joffrin, E., Alper, B., Andrew, Y., Beaumont, P., Beurskens, M., Boboc, A., Botrugno, A., Brix, M., Calabrò, G., Coffey, I., Conroy, S., Ford, O., Frigione, D., Garcia, J., ... JET-EFDA contributors (2012). Improved confinement in JET hybrid discharges. Plasma Physics and Controlled Fusion, 54(9), Article 095001. https://doi.org/10.1088/0741-3335/54/9/095001

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title = "Improved confinement in JET hybrid discharges",

abstract = "A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.",

author = "J. Hobirk and F. Imbeaux and F. Crisanti and P. Buratti and C.D. Challis and E. Joffrin and B. Alper and Y. Andrew and P. Beaumont and M. Beurskens and A. Boboc and A. Botrugno and M. Brix and G. Calabr{\`o} and I. Coffey and S. Conroy and O. Ford and D. Frigione and Joan Garcia and C. Giroud and N.C. Hawkes and D. Howell and I. Jenkins and D. Keeling and M. Kempenaars and H. Leggate and P. Lotte and {De La Luna}, E. and G.P. Maddison and P. Mantica and C. Mazzotta and D.C. McDonald and A. Meigs and I. Nunes and E. Rachlew and F. Rimini and M. Schneider and A.C.C. Sips and J.K. Stober and W. Studholme and Tuomas Tala and M. Tsalas and I. Voitsekhovitch and {de Vries}, P.C. and {JET-EFDA contributors}",

year = "2012",

doi = "10.1088/0741-3335/54/9/095001",

language = "English",

volume = "54",

journal = "Plasma Physics and Controlled Fusion",

issn = "0741-3335",

publisher = "Institute of Physics IOP",

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Hobirk, J, Imbeaux, F, Crisanti, F, Buratti, P, Challis, CD, Joffrin, E, Alper, B, Andrew, Y, Beaumont, P, Beurskens, M, Boboc, A, Botrugno, A, Brix, M, Calabrò, G, Coffey, I, Conroy, S, Ford, O, Frigione, D, Garcia, J, Giroud, C, Hawkes, NC, Howell, D, Jenkins, I, Keeling, D, Kempenaars, M, Leggate, H, Lotte, P, De La Luna, E, Maddison, GP, Mantica, P, Mazzotta, C, McDonald, DC, Meigs, A, Nunes, I, Rachlew, E, Rimini, F, Schneider, M, Sips, ACC, Stober, JK, Studholme, W, Tala, T, Tsalas, M, Voitsekhovitch, I, de Vries, PC & JET-EFDA contributors 2012, 'Improved confinement in JET hybrid discharges', Plasma Physics and Controlled Fusion, vol. 54, no. 9, 095001. https://doi.org/10.1088/0741-3335/54/9/095001

TY - JOUR

T1 - Improved confinement in JET hybrid discharges

AU - Hobirk, J.

AU - Imbeaux, F.

AU - Crisanti, F.

AU - Buratti, P.

AU - Challis, C.D.

AU - Joffrin, E.

AU - Alper, B.

AU - Andrew, Y.

AU - Beaumont, P.

AU - Beurskens, M.

AU - Boboc, A.

AU - Botrugno, A.

AU - Brix, M.

AU - Calabrò, G.

AU - Coffey, I.

AU - Conroy, S.

AU - Ford, O.

AU - Frigione, D.

AU - Garcia, Joan

AU - Giroud, C.

AU - Hawkes, N.C.

AU - Howell, D.

AU - Jenkins, I.

AU - Keeling, D.

AU - Kempenaars, M.

AU - Leggate, H.

AU - Lotte, P.

AU - De La Luna, E.

AU - Maddison, G.P.

AU - Mantica, P.

AU - Mazzotta, C.

AU - McDonald, D.C.

AU - Meigs, A.

AU - Nunes, I.

AU - Rachlew, E.

AU - Rimini, F.

AU - Schneider, M.

AU - Sips, A.C.C.

AU - Stober, J.K.

AU - Studholme, W.

AU - Tala, Tuomas

AU - Tsalas, M.

AU - Voitsekhovitch, I.

AU - de Vries, P.C.

AU - JET-EFDA contributors

PY - 2012

Y1 - 2012

N2 - A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

AB - A new technique has been developed to produce plasmas with improved confinement relative to the H98,y2 scaling law (ITER Physics Expert Groups on Confinement and Transport and Confinement Modelling and Database ITER Physics Basics Editors and ITER EDA 1999 Nucl. Fusion 39 2175) on the JET tokamak. In the mid-size tokamaks ASDEX upgrade and DIII-D heating during the current formation is used to produce a flat q-profile with a minimum close to 1. On JET this technique leads to q-profiles with similar minimum q but opposite to the other tokamaks not to an improved confinement state. By changing the method utilizing a faster current ramp with temporary higher current than in the flattop (current overshoot) plasmas with improved confinement (H98,y2 = 1.35) and good stability (βN ≈ 3) have been produced and extended to many confinement times only limited by technical constraints. The increase in H98,y2-factor is stronger with more heating power as can be seen in a power scan. The q-profile development during the high power phase in JET is reproduced by current diffusion calculated by TRANSP and CRONOS. Therefore the modifications produced by the current overshoot disappear quickly from the edge but the confinement improvement lasts longer, in some cases up to the end of the heating phase.

U2 - 10.1088/0741-3335/54/9/095001

DO - 10.1088/0741-3335/54/9/095001

M3 - Article

SN - 0741-3335

VL - 54

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

IS - 9

M1 - 095001

ER -

Improved confinement in JET hybrid discharges

Abstract

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