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Title: Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario

Time-dependent simulations are used to evolve plasma discharges in combination with a Modified Rutherford equation (MRE) for calculation of Neoclassical Tearing Mode (NTM) stability in response to Electron Cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. These simulations indicate that it is critical to detect the island as soon as possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2,1). A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2,1)-NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in themore » ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the Upper Launcher during the entire flattop phase. By assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10.« less
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [2] ;  [1] ;  [3] ;  [4] ;  [5]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. ITER Organization, St. Paul Lez Durance (France)
  3. Max Planck Inst. for Plasma Physics, Munich (Germany)
  4. Consiglio Nazionale delle Ricerche (CNR), Roma (Italy). Inst. of Plasma Physics
  5. National Research Council (CNR), Milan (Italy). Inst. of Plasma Physics (IFP)
Publication Date:
Grant/Contract Number:
AC02- 09CH11466
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 1; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1395336

Poli, Francesca M., Fredrickson, Eric, Henderson, Mark A., Kim, Sun-Hee, Bertelli, Nicola, Poli, Emanuele, Farina, Daniela, and Figini, Lorenzo. Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario. United States: N. p., Web. doi:10.1088/1741-4326/aa8e0b.
Poli, Francesca M., Fredrickson, Eric, Henderson, Mark A., Kim, Sun-Hee, Bertelli, Nicola, Poli, Emanuele, Farina, Daniela, & Figini, Lorenzo. Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario. United States. doi:10.1088/1741-4326/aa8e0b.
Poli, Francesca M., Fredrickson, Eric, Henderson, Mark A., Kim, Sun-Hee, Bertelli, Nicola, Poli, Emanuele, Farina, Daniela, and Figini, Lorenzo. 2017. "Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario". United States. doi:10.1088/1741-4326/aa8e0b. https://www.osti.gov/servlets/purl/1395336.
@article{osti_1395336,
title = {Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario},
author = {Poli, Francesca M. and Fredrickson, Eric and Henderson, Mark A. and Kim, Sun-Hee and Bertelli, Nicola and Poli, Emanuele and Farina, Daniela and Figini, Lorenzo},
abstractNote = {Time-dependent simulations are used to evolve plasma discharges in combination with a Modified Rutherford equation (MRE) for calculation of Neoclassical Tearing Mode (NTM) stability in response to Electron Cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. These simulations indicate that it is critical to detect the island as soon as possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2,1). A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2,1)-NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in the ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the Upper Launcher during the entire flattop phase. By assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10.},
doi = {10.1088/1741-4326/aa8e0b},
journal = {Nuclear Fusion},
number = 1,
volume = 58,
place = {United States},
year = {2017},
month = {9}
}