Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

E. Westerhof; O. Sauter; M. L. Mayoral; D. F. Howell; M. J. Mantsinen; M. F.F. Nave; B. Alper; C. Angioni; P. Belo; R. J. Buttery; A. Gondhalekar; T. Hellsten; T. C. Hender; T. Johnson; P. Lamalle; M. E. Maraschek; K. G. McClements; F. Nguyen; A. L. Pécquet; S. Podda; J. Rapp; S. E. Sharapov; M. Zabiego

doi:10.1088/0029-5515/42/11/306

Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

E. Westerhof, O. Sauter, M. L. Mayoral, D. F. Howell, M. J. Mantsinen, M. F.F. Nave, B. Alper, C. Angioni, P. Belo, R. J. Buttery, A. Gondhalekar, T. Hellsten, T. C. Hender, T. Johnson, P. Lamalle, M. E. Maraschek, K. G. McClements, F. Nguyen, A. L. Pécquet, S. PoddaJ. Rapp, S. E. Sharapov, M. Zabiego

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Abstract

A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, β_Nonset, is increased. The scenario has been explored experimentally in the Joint European Toms (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing β_Nonset, the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilized by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and β_Nonset is increased above its value obtained in discharges with additional heating from neutral beam injection alone.

Original language	English
Pages (from-to)	1324-1334
Number of pages	11
Journal	Nuclear Fusion
Volume	42
Issue number	11
DOIs	https://doi.org/10.1088/0029-5515/42/11/306
State	Published - Nov 2002
Externally published	Yes

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Westerhof, E., Sauter, O., Mayoral, M. L., Howell, D. F., Mantsinen, M. J., Nave, M. F. F., Alper, B., Angioni, C., Belo, P., Buttery, R. J., Gondhalekar, A., Hellsten, T., Hender, T. C., Johnson, T., Lamalle, P., Maraschek, M. E., McClements, K. G., Nguyen, F., Pécquet, A. L., ... Zabiego, M. (2002). Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET. Nuclear Fusion, 42(11), 1324-1334. https://doi.org/10.1088/0029-5515/42/11/306

@article{219884763cf54fa1b8925dab4cea2a49,

title = "Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET",

abstract = "A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, βNonset, is increased. The scenario has been explored experimentally in the Joint European Toms (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing βNonset, the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilized by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and βNonset is increased above its value obtained in discharges with additional heating from neutral beam injection alone.",

author = "E. Westerhof and O. Sauter and Mayoral, {M. L.} and Howell, {D. F.} and Mantsinen, {M. J.} and Nave, {M. F.F.} and B. Alper and C. Angioni and P. Belo and Buttery, {R. J.} and A. Gondhalekar and T. Hellsten and Hender, {T. C.} and T. Johnson and P. Lamalle and Maraschek, {M. E.} and McClements, {K. G.} and F. Nguyen and P{\'e}cquet, {A. L.} and S. Podda and J. Rapp and Sharapov, {S. E.} and M. Zabiego",

year = "2002",

month = nov,

doi = "10.1088/0029-5515/42/11/306",

language = "English",

volume = "42",

pages = "1324--1334",

journal = "Nuclear Fusion",

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Westerhof, E, Sauter, O, Mayoral, ML, Howell, DF, Mantsinen, MJ, Nave, MFF, Alper, B, Angioni, C, Belo, P, Buttery, RJ, Gondhalekar, A, Hellsten, T, Hender, TC, Johnson, T, Lamalle, P, Maraschek, ME, McClements, KG, Nguyen, F, Pécquet, AL, Podda, S, Rapp, J, Sharapov, SE & Zabiego, M 2002, 'Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET', Nuclear Fusion, vol. 42, no. 11, pp. 1324-1334. https://doi.org/10.1088/0029-5515/42/11/306

TY - JOUR

T1 - Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

AU - Westerhof, E.

AU - Sauter, O.

AU - Mayoral, M. L.

AU - Howell, D. F.

AU - Mantsinen, M. J.

AU - Nave, M. F.F.

AU - Alper, B.

AU - Angioni, C.

AU - Belo, P.

AU - Buttery, R. J.

AU - Gondhalekar, A.

AU - Hellsten, T.

AU - Hender, T. C.

AU - Johnson, T.

AU - Lamalle, P.

AU - Maraschek, M. E.

AU - McClements, K. G.

AU - Nguyen, F.

AU - Pécquet, A. L.

AU - Podda, S.

AU - Rapp, J.

AU - Sharapov, S. E.

AU - Zabiego, M.

PY - 2002/11

Y1 - 2002/11

N2 - A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, βNonset, is increased. The scenario has been explored experimentally in the Joint European Toms (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing βNonset, the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilized by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and βNonset is increased above its value obtained in discharges with additional heating from neutral beam injection alone.

AB - A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalized plasma pressure for triggering of NTMs, βNonset, is increased. The scenario has been explored experimentally in the Joint European Toms (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilization, favouring the triggering of NTMs and reducing βNonset, the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilized by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and βNonset is increased above its value obtained in discharges with additional heating from neutral beam injection alone.

UR - http://www.scopus.com/inward/record.url?scp=0036852665&partnerID=8YFLogxK

U2 - 10.1088/0029-5515/42/11/306

DO - 10.1088/0029-5515/42/11/306

M3 - Article

AN - SCOPUS:0036852665

SN - 0029-5515

VL - 42

SP - 1324

EP - 1334

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 11

ER -

Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET

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