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Title: Safety-factor profile tailoring by improved electron cyclotron system for sawtooth control and reverse shear scenarios in ITER

Abstract

The effect of the predicted local electron cyclotron current driven by the optimized electron cyclotron system on ITER is discussed. A design variant was recently proposed to enlarge the physics program covered by the upper and equatorial launchers. By extending the functionality range of the upper launcher, significant control capabilities of the sawtooth period can be obtained. The upper launcher improvement still allows enough margin to exceed the requirements for neoclassical tearing mode stabilization, for which it was originally designed. The analysis of the sawtooth control is carried on with the ASTRA transport code, coupled with the threshold model by Por-celli, to study the control capabilities of the improved upper launcher on the sawtooth instability. The simulations take into account the significant stabilizing effect of the fusion alpha particles. The sawtooth period can be increased by a factor of 1.5 with co-ECCD outside the q = 1 surface, and decreased by at least 30% with co-ECCD inside q = 1. The present ITER base-line design has the electron cyclotron launchers providing only co-ECCD. The variant for the equatorial launcher proposes the possibility to drive counter-ECCD with 1 of the 3 rows of mirrors: the counter-ECCD can then be balanced withmore » co-ECCD and provide pure ECH with no net driven current. The difference between full co-ECCD off-axis using all 20MW from the equatorial launcher and 20MW co-ECCD driven by 2/3 from the equatorial launcher and 1/3 from the upper launcher is shown to be negligible. Cnt-ECCD also offers greater control of the plasma current density, therefore this analysis addresses the performance of the equatorial launcher to control the central q profile. The equatorial launcher is shown to control very efficiently the value of q{sub 0.2}-q{sub min} in advanced scenarios, if one row provides counter-ECCD.« less

Authors:
; ;  [1]; ;  [2]; ;  [3];  [4];  [5]
  1. Ecole Polytechnique Federate de Lausanne, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, CH-1015 Lausanne (Switzerland)
  2. ITER Organization, CHD Dpt, CEN Cadarache 519/007, 13108 Saint-Paul-les-Durance (France)
  3. Istituto di Fisica del Plasma, EURATOM-Enea-CNR Association, Milano (Italy)
  4. Fusion for Energy, c/Josep Pla, 08019 Barcelona (Spain)
  5. Max Planck Institut fuer Plasmaphysik IPP-EURATOM Association, Garching (Germany)
Publication Date:
OSTI Identifier:
21251761
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1069; Journal Issue: 1; Conference: Joint Varenna-Lausanne international workshop on theory of fusion plasmas, Varenna (Italy), 25-29 Aug 2008; Other Information: DOI: 10.1063/1.3033728; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALPHA PARTICLES; CYCLOTRON RESONANCE; CYCLOTRONS; ECR CURRENT DRIVE; ECR HEATING; ELECTRIC CURRENTS; ITER TOKAMAK; MICROWAVE AMPLIFIERS; NEOCLASSICAL TRANSPORT THEORY; SAWTOOTH OSCILLATIONS; SIMULATION; TEARING INSTABILITY

Citation Formats

Zucca, C., Sauter, O., Fable, E., Henderson, M. A., Polevoi, A., Farina, D., Ramponi, G., Saibene, G., and Zohm, H. Safety-factor profile tailoring by improved electron cyclotron system for sawtooth control and reverse shear scenarios in ITER. United States: N. p., 2008. Web. doi:10.1063/1.3033728.
Zucca, C., Sauter, O., Fable, E., Henderson, M. A., Polevoi, A., Farina, D., Ramponi, G., Saibene, G., & Zohm, H. Safety-factor profile tailoring by improved electron cyclotron system for sawtooth control and reverse shear scenarios in ITER. United States. doi:10.1063/1.3033728.
Zucca, C., Sauter, O., Fable, E., Henderson, M. A., Polevoi, A., Farina, D., Ramponi, G., Saibene, G., and Zohm, H. Sat . "Safety-factor profile tailoring by improved electron cyclotron system for sawtooth control and reverse shear scenarios in ITER". United States. doi:10.1063/1.3033728.
@article{osti_21251761,
title = {Safety-factor profile tailoring by improved electron cyclotron system for sawtooth control and reverse shear scenarios in ITER},
author = {Zucca, C. and Sauter, O. and Fable, E. and Henderson, M. A. and Polevoi, A. and Farina, D. and Ramponi, G. and Saibene, G. and Zohm, H.},
abstractNote = {The effect of the predicted local electron cyclotron current driven by the optimized electron cyclotron system on ITER is discussed. A design variant was recently proposed to enlarge the physics program covered by the upper and equatorial launchers. By extending the functionality range of the upper launcher, significant control capabilities of the sawtooth period can be obtained. The upper launcher improvement still allows enough margin to exceed the requirements for neoclassical tearing mode stabilization, for which it was originally designed. The analysis of the sawtooth control is carried on with the ASTRA transport code, coupled with the threshold model by Por-celli, to study the control capabilities of the improved upper launcher on the sawtooth instability. The simulations take into account the significant stabilizing effect of the fusion alpha particles. The sawtooth period can be increased by a factor of 1.5 with co-ECCD outside the q = 1 surface, and decreased by at least 30% with co-ECCD inside q = 1. The present ITER base-line design has the electron cyclotron launchers providing only co-ECCD. The variant for the equatorial launcher proposes the possibility to drive counter-ECCD with 1 of the 3 rows of mirrors: the counter-ECCD can then be balanced with co-ECCD and provide pure ECH with no net driven current. The difference between full co-ECCD off-axis using all 20MW from the equatorial launcher and 20MW co-ECCD driven by 2/3 from the equatorial launcher and 1/3 from the upper launcher is shown to be negligible. Cnt-ECCD also offers greater control of the plasma current density, therefore this analysis addresses the performance of the equatorial launcher to control the central q profile. The equatorial launcher is shown to control very efficiently the value of q{sub 0.2}-q{sub min} in advanced scenarios, if one row provides counter-ECCD.},
doi = {10.1063/1.3033728},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1069,
place = {United States},
year = {2008},
month = {11}
}