Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers

A. Ekedahl, G. Granucci, J. Mailloux, Y. Baranov, S.K. Erents, E. Joffrin, X. Litaudon, A. Loarte, P.J. Lomas, D.C. McDonald, V. Petrzilka, Karin Rantamäki, F.G. Rimini, C. Silva, M. Stamp, A.A. Tuccillo, JET-EFDA Contributors

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Abstract

Efficient coupling of lower hybrid (LH) waves in conditions close to those foreseen in ITER has been obtained in advanced scenario plasmas in the JET tokamak. Up to 3 MW of lower hybrid current drive (LHCD) power has been coupled at a distance between the separatrix and the launcher of 11 cm, in the presence of edge localized mode activity. The key to the improved LH wave coupling is local control of the Scrape-Off-Layer (SOL) density through gas injection in the region magnetically connected to the launcher. This increases the electron density in front of the launcher so as to improve the coupling of the LH waves, i.e. reduce the reflected power in the launcher. The average power reflection coefficient was 5.7% with gas injection, at 11 cm distance between the separatrix and the launcher. A change in the gas injection design has made the gas puffing more efficient, making the use of D2 injection possible as an alternative to CD4. At similar injected electrons/s rates, D2 gives higher electron density in the SOL than CD4, resulting in better LH coupling with D2. The possibility of using D2 instead of the earlier used CD4 is an encouraging result in view of ITER operation, as CD4 may not be compatible in ITER due to the problem of tritium retention in deposited carbon layers.
Original languageEnglish
Pages (from-to)351 - 359
Number of pages9
JournalNuclear Fusion
Volume45
Issue number5
DOIs
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed

Fingerprint

launchers
gas injection
tritium
injection
reflectance
carbon
gases
electrons

Keywords

  • JET
  • plasma
  • fusion energy
  • fusion reactors
  • ITER

Cite this

Ekedahl, A., Granucci, G., Mailloux, J., Baranov, Y., Erents, S. K., Joffrin, E., ... JET-EFDA Contributors (2005). Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers. Nuclear Fusion, 45(5), 351 - 359. https://doi.org/10.1088/0029-5515/45/5/005
Ekedahl, A. ; Granucci, G. ; Mailloux, J. ; Baranov, Y. ; Erents, S.K. ; Joffrin, E. ; Litaudon, X. ; Loarte, A. ; Lomas, P.J. ; McDonald, D.C. ; Petrzilka, V. ; Rantamäki, Karin ; Rimini, F.G. ; Silva, C. ; Stamp, M. ; Tuccillo, A.A. ; JET-EFDA Contributors. / Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers. In: Nuclear Fusion. 2005 ; Vol. 45, No. 5. pp. 351 - 359.
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title = "Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers",
abstract = "Efficient coupling of lower hybrid (LH) waves in conditions close to those foreseen in ITER has been obtained in advanced scenario plasmas in the JET tokamak. Up to 3 MW of lower hybrid current drive (LHCD) power has been coupled at a distance between the separatrix and the launcher of 11 cm, in the presence of edge localized mode activity. The key to the improved LH wave coupling is local control of the Scrape-Off-Layer (SOL) density through gas injection in the region magnetically connected to the launcher. This increases the electron density in front of the launcher so as to improve the coupling of the LH waves, i.e. reduce the reflected power in the launcher. The average power reflection coefficient was 5.7{\%} with gas injection, at 11 cm distance between the separatrix and the launcher. A change in the gas injection design has made the gas puffing more efficient, making the use of D2 injection possible as an alternative to CD4. At similar injected electrons/s rates, D2 gives higher electron density in the SOL than CD4, resulting in better LH coupling with D2. The possibility of using D2 instead of the earlier used CD4 is an encouraging result in view of ITER operation, as CD4 may not be compatible in ITER due to the problem of tritium retention in deposited carbon layers.",
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author = "A. Ekedahl and G. Granucci and J. Mailloux and Y. Baranov and S.K. Erents and E. Joffrin and X. Litaudon and A. Loarte and P.J. Lomas and D.C. McDonald and V. Petrzilka and Karin Rantam{\"a}ki and F.G. Rimini and C. Silva and M. Stamp and A.A. Tuccillo and {JET-EFDA Contributors}",
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Ekedahl, A, Granucci, G, Mailloux, J, Baranov, Y, Erents, SK, Joffrin, E, Litaudon, X, Loarte, A, Lomas, PJ, McDonald, DC, Petrzilka, V, Rantamäki, K, Rimini, FG, Silva, C, Stamp, M, Tuccillo, AA & JET-EFDA Contributors 2005, 'Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers', Nuclear Fusion, vol. 45, no. 5, pp. 351 - 359. https://doi.org/10.1088/0029-5515/45/5/005

Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers. / Ekedahl, A.; Granucci, G.; Mailloux, J.; Baranov, Y.; Erents, S.K.; Joffrin, E.; Litaudon, X.; Loarte, A.; Lomas, P.J.; McDonald, D.C.; Petrzilka, V.; Rantamäki, Karin; Rimini, F.G.; Silva, C.; Stamp, M.; Tuccillo, A.A.; JET-EFDA Contributors.

In: Nuclear Fusion, Vol. 45, No. 5, 2005, p. 351 - 359.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Long distance coupling of lower hybrid waves in JET plasmas with edge and core transport barriers

AU - Ekedahl, A.

AU - Granucci, G.

AU - Mailloux, J.

AU - Baranov, Y.

AU - Erents, S.K.

AU - Joffrin, E.

AU - Litaudon, X.

AU - Loarte, A.

AU - Lomas, P.J.

AU - McDonald, D.C.

AU - Petrzilka, V.

AU - Rantamäki, Karin

AU - Rimini, F.G.

AU - Silva, C.

AU - Stamp, M.

AU - Tuccillo, A.A.

AU - JET-EFDA Contributors, null

PY - 2005

Y1 - 2005

N2 - Efficient coupling of lower hybrid (LH) waves in conditions close to those foreseen in ITER has been obtained in advanced scenario plasmas in the JET tokamak. Up to 3 MW of lower hybrid current drive (LHCD) power has been coupled at a distance between the separatrix and the launcher of 11 cm, in the presence of edge localized mode activity. The key to the improved LH wave coupling is local control of the Scrape-Off-Layer (SOL) density through gas injection in the region magnetically connected to the launcher. This increases the electron density in front of the launcher so as to improve the coupling of the LH waves, i.e. reduce the reflected power in the launcher. The average power reflection coefficient was 5.7% with gas injection, at 11 cm distance between the separatrix and the launcher. A change in the gas injection design has made the gas puffing more efficient, making the use of D2 injection possible as an alternative to CD4. At similar injected electrons/s rates, D2 gives higher electron density in the SOL than CD4, resulting in better LH coupling with D2. The possibility of using D2 instead of the earlier used CD4 is an encouraging result in view of ITER operation, as CD4 may not be compatible in ITER due to the problem of tritium retention in deposited carbon layers.

AB - Efficient coupling of lower hybrid (LH) waves in conditions close to those foreseen in ITER has been obtained in advanced scenario plasmas in the JET tokamak. Up to 3 MW of lower hybrid current drive (LHCD) power has been coupled at a distance between the separatrix and the launcher of 11 cm, in the presence of edge localized mode activity. The key to the improved LH wave coupling is local control of the Scrape-Off-Layer (SOL) density through gas injection in the region magnetically connected to the launcher. This increases the electron density in front of the launcher so as to improve the coupling of the LH waves, i.e. reduce the reflected power in the launcher. The average power reflection coefficient was 5.7% with gas injection, at 11 cm distance between the separatrix and the launcher. A change in the gas injection design has made the gas puffing more efficient, making the use of D2 injection possible as an alternative to CD4. At similar injected electrons/s rates, D2 gives higher electron density in the SOL than CD4, resulting in better LH coupling with D2. The possibility of using D2 instead of the earlier used CD4 is an encouraging result in view of ITER operation, as CD4 may not be compatible in ITER due to the problem of tritium retention in deposited carbon layers.

KW - JET

KW - plasma

KW - fusion energy

KW - fusion reactors

KW - ITER

U2 - 10.1088/0029-5515/45/5/005

DO - 10.1088/0029-5515/45/5/005

M3 - Article

VL - 45

SP - 351

EP - 359

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 5

ER -