Expanding the operating space of ICRF on JET with a view to ITER

P.U. Lamalle, M.J. Mantsinen, J.-M. Noterdaeme, B. Alper, P. Beaumont, L. Bertalot, T. Blackman, Vl.V. Bobkov, G. Bonheure, J. Brzozowski, C. Castaldo, S. Conroy, M. de Baar, E. de la Luna, P. de Vries, F. Durodié, G. Ericsson, L.-G. Eriksson, C. Gowers, R. FeltonJukka Heikkinen, T. Hellsten, V. Kiptily, K. Lawson, M. Laxåback, E. Lerche, P. Lomas, A. Lyssoivan, M.-L. Mayoral, F. Meo, M. Mirnov, I. Monakhov, I. Nunes, S. Popovichev, A. Salmi, M.I.K. Santala, S. Sharapov, Tuomas Tala, M. Tardocchi, D. Van Eester, B. Weyssow, JET-EFDA Contributors

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

This paper reports on ITER-relevant ion cyclotron resonance frequency (ICRF) physics investigated on JET in 2003 and early 2004. Minority heating of helium three in hydrogen plasmas—(3He)H—was systematically explored by varying the 3He concentration and the toroidal phasing of the antenna arrays. The best heating performance (a maximum electron temperature of 6.2 keV with 5 MW of ICRF power) was obtained with a preferential wave launch in the direction of the plasma current. A clear experimental demonstration was made of the sharp and reproducible transition to the mode conversion heating regime when the 3He concentration increased above ~2%. In the latter regime the best heating performance (a maximum electron temperature of 8 keV with 5 MW of ICRF power) was achieved with dipole array phasing, i.e. a symmetric antenna power spectrum. Minority heating of deuterium in hydrogen plasmas—(D)H—was also investigated but was found inaccessible because this scenario is too sensitive to impurity ions with Z/A = 1/2 such as C6+, small amounts of which directly lead into the mode conversion regime. Minority heating of up to 3% of tritium in deuterium plasmas was systematically investigated during the JET trace tritium experimental campaign (TTE). This required operating JET at its highest possible magnetic field (3.9 to 4 T) and the ICRF system at its lowest frequency (23 MHz). The interest of this scenario for ICRF heating at these low concentrations and its efficiency at boosting the suprathermal neutron yield were confirmed, and the measured neutron and gammay ray spectra permit interesting comparisons with advanced ICRF code simulations. Investigations of finite Larmor radius effects on the RF-induced high-energy tails during second harmonic (ω = 2ωc) heating of a hydrogen minority in D plasmas clearly demonstrated a strong decrease in the RF diffusion coefficient at proton energies ~ 1 MeV, in agreement with theoretical expectations. Fast wave heating and current drive experiments in deuterium plasmas showed effective direct electron heating with dipole phasing of the antennas, but only small changes of the central plasma current density were observed with the directive phasings, in particular at low single pass damping. New investigations of the heating efficiency of ICRF antennas confirmed its strong dependence on the parallel wavenumber spectrum. Advances in topics of a more technological nature are also summarized: ELM studies using fast RF measurements, the successful experimental demonstration of a new ELM-tolerant antenna matching scheme and technical enhancements planned on the JET ICRF system for 2006, they being equally strongly driven by the preparation for ITER.
Original languageEnglish
Pages (from-to)391-400
Number of pages10
JournalNuclear Fusion
Volume46
Issue number2
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Fingerprint

cyclotron resonance
heating
ions
minorities
antennas
deuterium plasma
plasma currents
hydrogen plasma
tritium
electron energy
dipoles
neutrons
Larmor radius
antenna arrays
proton energy
power spectra
deuterium
low concentrations
rays
diffusion coefficient

Keywords

  • JET
  • plasma
  • fusion energy
  • fusion reactors
  • ITER
  • ion cyclotron resonance frequency

Cite this

Lamalle, P. U., Mantsinen, M. J., Noterdaeme, J-M., Alper, B., Beaumont, P., Bertalot, L., ... JET-EFDA Contributors (2006). Expanding the operating space of ICRF on JET with a view to ITER. Nuclear Fusion, 46(2), 391-400. https://doi.org/10.1088/0029-5515/46/2/021
Lamalle, P.U. ; Mantsinen, M.J. ; Noterdaeme, J.-M. ; Alper, B. ; Beaumont, P. ; Bertalot, L. ; Blackman, T. ; Bobkov, Vl.V. ; Bonheure, G. ; Brzozowski, J. ; Castaldo, C. ; Conroy, S. ; de Baar, M. ; de la Luna, E. ; de Vries, P. ; Durodié, F. ; Ericsson, G. ; Eriksson, L.-G. ; Gowers, C. ; Felton, R. ; Heikkinen, Jukka ; Hellsten, T. ; Kiptily, V. ; Lawson, K. ; Laxåback, M. ; Lerche, E. ; Lomas, P. ; Lyssoivan, A. ; Mayoral, M.-L. ; Meo, F. ; Mirnov, M. ; Monakhov, I. ; Nunes, I. ; Popovichev, S. ; Salmi, A. ; Santala, M.I.K. ; Sharapov, S. ; Tala, Tuomas ; Tardocchi, M. ; Van Eester, D. ; Weyssow, B. ; JET-EFDA Contributors. / Expanding the operating space of ICRF on JET with a view to ITER. In: Nuclear Fusion. 2006 ; Vol. 46, No. 2. pp. 391-400.
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abstract = "This paper reports on ITER-relevant ion cyclotron resonance frequency (ICRF) physics investigated on JET in 2003 and early 2004. Minority heating of helium three in hydrogen plasmas—(3He)H—was systematically explored by varying the 3He concentration and the toroidal phasing of the antenna arrays. The best heating performance (a maximum electron temperature of 6.2 keV with 5 MW of ICRF power) was obtained with a preferential wave launch in the direction of the plasma current. A clear experimental demonstration was made of the sharp and reproducible transition to the mode conversion heating regime when the 3He concentration increased above ~2{\%}. In the latter regime the best heating performance (a maximum electron temperature of 8 keV with 5 MW of ICRF power) was achieved with dipole array phasing, i.e. a symmetric antenna power spectrum. Minority heating of deuterium in hydrogen plasmas—(D)H—was also investigated but was found inaccessible because this scenario is too sensitive to impurity ions with Z/A = 1/2 such as C6+, small amounts of which directly lead into the mode conversion regime. Minority heating of up to 3{\%} of tritium in deuterium plasmas was systematically investigated during the JET trace tritium experimental campaign (TTE). This required operating JET at its highest possible magnetic field (3.9 to 4 T) and the ICRF system at its lowest frequency (23 MHz). The interest of this scenario for ICRF heating at these low concentrations and its efficiency at boosting the suprathermal neutron yield were confirmed, and the measured neutron and gammay ray spectra permit interesting comparisons with advanced ICRF code simulations. Investigations of finite Larmor radius effects on the RF-induced high-energy tails during second harmonic (ω = 2ωc) heating of a hydrogen minority in D plasmas clearly demonstrated a strong decrease in the RF diffusion coefficient at proton energies ~ 1 MeV, in agreement with theoretical expectations. Fast wave heating and current drive experiments in deuterium plasmas showed effective direct electron heating with dipole phasing of the antennas, but only small changes of the central plasma current density were observed with the directive phasings, in particular at low single pass damping. New investigations of the heating efficiency of ICRF antennas confirmed its strong dependence on the parallel wavenumber spectrum. Advances in topics of a more technological nature are also summarized: ELM studies using fast RF measurements, the successful experimental demonstration of a new ELM-tolerant antenna matching scheme and technical enhancements planned on the JET ICRF system for 2006, they being equally strongly driven by the preparation for ITER.",
keywords = "JET, plasma, fusion energy, fusion reactors, ITER, ion cyclotron resonance frequency",
author = "P.U. Lamalle and M.J. Mantsinen and J.-M. Noterdaeme and B. Alper and P. Beaumont and L. Bertalot and T. Blackman and Vl.V. Bobkov and G. Bonheure and J. Brzozowski and C. Castaldo and S. Conroy and {de Baar}, M. and {de la Luna}, E. and {de Vries}, P. and F. Durodi{\'e} and G. Ericsson and L.-G. Eriksson and C. Gowers and R. Felton and Jukka Heikkinen and T. Hellsten and V. Kiptily and K. Lawson and M. Lax{\aa}back and E. Lerche and P. Lomas and A. Lyssoivan and M.-L. Mayoral and F. Meo and M. Mirnov and I. Monakhov and I. Nunes and S. Popovichev and A. Salmi and M.I.K. Santala and S. Sharapov and Tuomas Tala and M. Tardocchi and {Van Eester}, D. and B. Weyssow and {JET-EFDA Contributors}",
year = "2006",
doi = "10.1088/0029-5515/46/2/021",
language = "English",
volume = "46",
pages = "391--400",
journal = "Nuclear Fusion",
issn = "0029-5515",
publisher = "Institute of Physics IOP",
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}

Lamalle, PU, Mantsinen, MJ, Noterdaeme, J-M, Alper, B, Beaumont, P, Bertalot, L, Blackman, T, Bobkov, VV, Bonheure, G, Brzozowski, J, Castaldo, C, Conroy, S, de Baar, M, de la Luna, E, de Vries, P, Durodié, F, Ericsson, G, Eriksson, L-G, Gowers, C, Felton, R, Heikkinen, J, Hellsten, T, Kiptily, V, Lawson, K, Laxåback, M, Lerche, E, Lomas, P, Lyssoivan, A, Mayoral, M-L, Meo, F, Mirnov, M, Monakhov, I, Nunes, I, Popovichev, S, Salmi, A, Santala, MIK, Sharapov, S, Tala, T, Tardocchi, M, Van Eester, D, Weyssow, B & JET-EFDA Contributors 2006, 'Expanding the operating space of ICRF on JET with a view to ITER', Nuclear Fusion, vol. 46, no. 2, pp. 391-400. https://doi.org/10.1088/0029-5515/46/2/021

Expanding the operating space of ICRF on JET with a view to ITER. / Lamalle, P.U.; Mantsinen, M.J.; Noterdaeme, J.-M.; Alper, B.; Beaumont, P.; Bertalot, L.; Blackman, T.; Bobkov, Vl.V.; Bonheure, G.; Brzozowski, J.; Castaldo, C.; Conroy, S.; de Baar, M.; de la Luna, E.; de Vries, P.; Durodié, F.; Ericsson, G.; Eriksson, L.-G.; Gowers, C.; Felton, R.; Heikkinen, Jukka; Hellsten, T.; Kiptily, V.; Lawson, K.; Laxåback, M.; Lerche, E.; Lomas, P.; Lyssoivan, A.; Mayoral, M.-L.; Meo, F.; Mirnov, M.; Monakhov, I.; Nunes, I.; Popovichev, S.; Salmi, A.; Santala, M.I.K.; Sharapov, S.; Tala, Tuomas; Tardocchi, M.; Van Eester, D.; Weyssow, B.; JET-EFDA Contributors.

In: Nuclear Fusion, Vol. 46, No. 2, 2006, p. 391-400.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Expanding the operating space of ICRF on JET with a view to ITER

AU - Lamalle, P.U.

AU - Mantsinen, M.J.

AU - Noterdaeme, J.-M.

AU - Alper, B.

AU - Beaumont, P.

AU - Bertalot, L.

AU - Blackman, T.

AU - Bobkov, Vl.V.

AU - Bonheure, G.

AU - Brzozowski, J.

AU - Castaldo, C.

AU - Conroy, S.

AU - de Baar, M.

AU - de la Luna, E.

AU - de Vries, P.

AU - Durodié, F.

AU - Ericsson, G.

AU - Eriksson, L.-G.

AU - Gowers, C.

AU - Felton, R.

AU - Heikkinen, Jukka

AU - Hellsten, T.

AU - Kiptily, V.

AU - Lawson, K.

AU - Laxåback, M.

AU - Lerche, E.

AU - Lomas, P.

AU - Lyssoivan, A.

AU - Mayoral, M.-L.

AU - Meo, F.

AU - Mirnov, M.

AU - Monakhov, I.

AU - Nunes, I.

AU - Popovichev, S.

AU - Salmi, A.

AU - Santala, M.I.K.

AU - Sharapov, S.

AU - Tala, Tuomas

AU - Tardocchi, M.

AU - Van Eester, D.

AU - Weyssow, B.

AU - JET-EFDA Contributors,

PY - 2006

Y1 - 2006

N2 - This paper reports on ITER-relevant ion cyclotron resonance frequency (ICRF) physics investigated on JET in 2003 and early 2004. Minority heating of helium three in hydrogen plasmas—(3He)H—was systematically explored by varying the 3He concentration and the toroidal phasing of the antenna arrays. The best heating performance (a maximum electron temperature of 6.2 keV with 5 MW of ICRF power) was obtained with a preferential wave launch in the direction of the plasma current. A clear experimental demonstration was made of the sharp and reproducible transition to the mode conversion heating regime when the 3He concentration increased above ~2%. In the latter regime the best heating performance (a maximum electron temperature of 8 keV with 5 MW of ICRF power) was achieved with dipole array phasing, i.e. a symmetric antenna power spectrum. Minority heating of deuterium in hydrogen plasmas—(D)H—was also investigated but was found inaccessible because this scenario is too sensitive to impurity ions with Z/A = 1/2 such as C6+, small amounts of which directly lead into the mode conversion regime. Minority heating of up to 3% of tritium in deuterium plasmas was systematically investigated during the JET trace tritium experimental campaign (TTE). This required operating JET at its highest possible magnetic field (3.9 to 4 T) and the ICRF system at its lowest frequency (23 MHz). The interest of this scenario for ICRF heating at these low concentrations and its efficiency at boosting the suprathermal neutron yield were confirmed, and the measured neutron and gammay ray spectra permit interesting comparisons with advanced ICRF code simulations. Investigations of finite Larmor radius effects on the RF-induced high-energy tails during second harmonic (ω = 2ωc) heating of a hydrogen minority in D plasmas clearly demonstrated a strong decrease in the RF diffusion coefficient at proton energies ~ 1 MeV, in agreement with theoretical expectations. Fast wave heating and current drive experiments in deuterium plasmas showed effective direct electron heating with dipole phasing of the antennas, but only small changes of the central plasma current density were observed with the directive phasings, in particular at low single pass damping. New investigations of the heating efficiency of ICRF antennas confirmed its strong dependence on the parallel wavenumber spectrum. Advances in topics of a more technological nature are also summarized: ELM studies using fast RF measurements, the successful experimental demonstration of a new ELM-tolerant antenna matching scheme and technical enhancements planned on the JET ICRF system for 2006, they being equally strongly driven by the preparation for ITER.

AB - This paper reports on ITER-relevant ion cyclotron resonance frequency (ICRF) physics investigated on JET in 2003 and early 2004. Minority heating of helium three in hydrogen plasmas—(3He)H—was systematically explored by varying the 3He concentration and the toroidal phasing of the antenna arrays. The best heating performance (a maximum electron temperature of 6.2 keV with 5 MW of ICRF power) was obtained with a preferential wave launch in the direction of the plasma current. A clear experimental demonstration was made of the sharp and reproducible transition to the mode conversion heating regime when the 3He concentration increased above ~2%. In the latter regime the best heating performance (a maximum electron temperature of 8 keV with 5 MW of ICRF power) was achieved with dipole array phasing, i.e. a symmetric antenna power spectrum. Minority heating of deuterium in hydrogen plasmas—(D)H—was also investigated but was found inaccessible because this scenario is too sensitive to impurity ions with Z/A = 1/2 such as C6+, small amounts of which directly lead into the mode conversion regime. Minority heating of up to 3% of tritium in deuterium plasmas was systematically investigated during the JET trace tritium experimental campaign (TTE). This required operating JET at its highest possible magnetic field (3.9 to 4 T) and the ICRF system at its lowest frequency (23 MHz). The interest of this scenario for ICRF heating at these low concentrations and its efficiency at boosting the suprathermal neutron yield were confirmed, and the measured neutron and gammay ray spectra permit interesting comparisons with advanced ICRF code simulations. Investigations of finite Larmor radius effects on the RF-induced high-energy tails during second harmonic (ω = 2ωc) heating of a hydrogen minority in D plasmas clearly demonstrated a strong decrease in the RF diffusion coefficient at proton energies ~ 1 MeV, in agreement with theoretical expectations. Fast wave heating and current drive experiments in deuterium plasmas showed effective direct electron heating with dipole phasing of the antennas, but only small changes of the central plasma current density were observed with the directive phasings, in particular at low single pass damping. New investigations of the heating efficiency of ICRF antennas confirmed its strong dependence on the parallel wavenumber spectrum. Advances in topics of a more technological nature are also summarized: ELM studies using fast RF measurements, the successful experimental demonstration of a new ELM-tolerant antenna matching scheme and technical enhancements planned on the JET ICRF system for 2006, they being equally strongly driven by the preparation for ITER.

KW - JET

KW - plasma

KW - fusion energy

KW - fusion reactors

KW - ITER

KW - ion cyclotron resonance frequency

U2 - 10.1088/0029-5515/46/2/021

DO - 10.1088/0029-5515/46/2/021

M3 - Article

VL - 46

SP - 391

EP - 400

JO - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 2

ER -

Lamalle PU, Mantsinen MJ, Noterdaeme J-M, Alper B, Beaumont P, Bertalot L et al. Expanding the operating space of ICRF on JET with a view to ITER. Nuclear Fusion. 2006;46(2):391-400. https://doi.org/10.1088/0029-5515/46/2/021