Impact of different heating and current drive methods on the early shape q-profile evolution in JET

Tuomas Tala (Corresponding Author), V. Parail, A. Becoulet, C. Challis, G. Corrigan, N. Hawkes, D. Heading, M. Mantsinen, S. Nowak, Contributors to the EFDA-JET Work Programme

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.
Original languageEnglish
Pages (from-to)1181-1202
JournalPlasma Physics and Controlled Fusion
Volume44
Issue number7
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

Preheating
Heating
heating
profiles
Cyclotron resonance
Electrons
Cyclotrons
beam injection
neutral beams
cyclotron resonance
Ions
shear
Joule heating
cyclotrons
electrons
ions
Plasmas

Keywords

  • JET
  • plasma
  • fusion energy
  • fusion reactors
  • tokamak
  • internal transport barriers
  • lower hybrid current drive
  • magnetic shear

Cite this

Tala, T., Parail, V., Becoulet, A., Challis, C., Corrigan, G., Hawkes, N., ... Programme, C. T. T. EFDA-JET. W. (2002). Impact of different heating and current drive methods on the early shape q-profile evolution in JET. Plasma Physics and Controlled Fusion, 44(7), 1181-1202. https://doi.org/10.1088/0741-3335/44/7/309
Tala, Tuomas ; Parail, V. ; Becoulet, A. ; Challis, C. ; Corrigan, G. ; Hawkes, N. ; Heading, D. ; Mantsinen, M. ; Nowak, S. ; Programme, Contributors to the EFDA-JET Work. / Impact of different heating and current drive methods on the early shape q-profile evolution in JET. In: Plasma Physics and Controlled Fusion. 2002 ; Vol. 44, No. 7. pp. 1181-1202.
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abstract = "Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.",
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Tala, T, Parail, V, Becoulet, A, Challis, C, Corrigan, G, Hawkes, N, Heading, D, Mantsinen, M, Nowak, S & Programme, CTTEFDA-JETW 2002, 'Impact of different heating and current drive methods on the early shape q-profile evolution in JET', Plasma Physics and Controlled Fusion, vol. 44, no. 7, pp. 1181-1202. https://doi.org/10.1088/0741-3335/44/7/309

Impact of different heating and current drive methods on the early shape q-profile evolution in JET. / Tala, Tuomas (Corresponding Author); Parail, V.; Becoulet, A.; Challis, C.; Corrigan, G.; Hawkes, N.; Heading, D.; Mantsinen, M.; Nowak, S.; Programme, Contributors to the EFDA-JET Work.

In: Plasma Physics and Controlled Fusion, Vol. 44, No. 7, 2002, p. 1181-1202.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Impact of different heating and current drive methods on the early shape q-profile evolution in JET

AU - Tala, Tuomas

AU - Parail, V.

AU - Becoulet, A.

AU - Challis, C.

AU - Corrigan, G.

AU - Hawkes, N.

AU - Heading, D.

AU - Mantsinen, M.

AU - Nowak, S.

AU - Programme, Contributors to the EFDA-JET Work

PY - 2002

Y1 - 2002

N2 - Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.

AB - Transport calculations illustrate that the lower hybrid current drive (LHCD) and off-axis electron cyclotron current drive (ECCD) are the only preheating methods that can create a wide, deeply reversed q-profile, i.e. large negative magnetic shear, on the JET tokamak. Off-axis neutral beam injection (NBI) and off-axis ion cyclotron resonance heating (ICRH) preheating yields a weakly reversed q-profile (small negative magnetic shear), whereas NBI and ICRH on-axis heating as well as ohmic preheating produce a monotonic q-profile in the preheating phase. Here, on-axis power deposition and current drive refers to heating and current drive at or close to magnetic axis and correspondingly, off-axis refers to heating and current drive deposited typically around the half minor radius (r/a = 0.3-0.6). The results on LHCD, ICRH and ohmic preheating have been verified in the recent JET experiments. The current drive efficiency scan shows that in the case of LHCD, ECCD and off-axis NBI, the driven current is absolutely crucial to obtain a reversed q-profile and to modify the current profile evolution drastically in the preheating phase. Taking into account only the direct electron heating effect, LHCD does not create a reversed q-profile. The timing scans indicate that the radial location of qmin at the end of the preheating phase is generally quite insensitive to the start time of the preheating, once started 0-2 s after the plasma initiation if the method relies upon the driven current. On the other hand, methods relying only upon electron heating are very sensitive to that. In both cases, the magnitude of the negative magnetic shear, however, seems to be very sensitive to the start time of the preheating.

KW - JET

KW - plasma

KW - fusion energy

KW - fusion reactors

KW - tokamak

KW - internal transport barriers

KW - lower hybrid current drive

KW - magnetic shear

U2 - 10.1088/0741-3335/44/7/309

DO - 10.1088/0741-3335/44/7/309

M3 - Article

VL - 44

SP - 1181

EP - 1202

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

SN - 0741-3335

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ER -