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Title: Combined magnetic and kinetic control of advanced tokamak steady state scenarios based on semi-empirical modelling

Our paper shows that semi-empirical data-driven models based on a two-time-scale approximation for the magnetic and kinetic control of advanced tokamak (AT) scenarios can be advantageously identified from simulated rather than real data, and used for control design. The method is applied to the combined control of the safety factor profile, q(x), and normalized pressure parameter, beta(N), using DIII-D parameters and actuators (on-axis co-current neutral beam injection (NBI) power, off-axis co-current NBI power, electron cyclotron current drive power, and ohmic coil). The approximate plasma response model was identified from simulated open-loop data obtained using a rapidly converging plasma transport code, METIS, which includes an MHD equilibrium and current diffusion solver, and combines plasma transport nonlinearity with 0D scaling laws and 1.5D ordinary differential equations. The paper discusses the results of closed-loop METIS simulations, using the near-optimal ARTAEMIS control algorithm (MoreauDet al 2013 Nucl. Fusion 53 063020) for steady stateAT operation. With feedforward plus feedback control, the steady state target q-profile and beta(N) are satisfactorily tracked with a time scale of about 10 s, despite large disturbances applied to the feedforward powers and plasma parameters. We also show the robustness of the control algorithm with respect to disturbances of the H&CDmore » actuators and of plasma parameters such as the H-factor, plasma density and effective charge.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [2] ;  [1] ;  [2] ;  [4] ;  [2] ;  [5] ;  [2]
  1. CEA, Saint-Paul-lez-Durance (France). Inst. for Magnetic Fusion Research
  2. General Atomics, San Diego, CA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Columbia Univ., New York, NY (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-741495
Journal ID: ISSN 0029-5515; AT1010101; ERAT355
Grant/Contract Number:
AC05-00OR22725; FC02-04ER54698; AC52-07NA27344; FG02-04ER54761
Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 55; Journal Issue: 6; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamaks; plasma control; plasma simulation; profile control; steady state operation scenarios; heating and current drive; TIME PROFILE CONTROL
OSTI Identifier:
1375957
Alternate Identifier(s):
OSTI ID: 1295124; OSTI ID: 1438695

Moreau, Didier, Artaud, J. F., Ferron, John R., Holcomb, Christopher T., Humphreys, David A., Liu, Feng, Luce, Timothy C., Park, Jin Myung, Prater, Ronald, Turco, Francesca, and Walker, Michael L.. Combined magnetic and kinetic control of advanced tokamak steady state scenarios based on semi-empirical modelling. United States: N. p., Web. doi:10.1088/0029-5515/55/6/063011.
Moreau, Didier, Artaud, J. F., Ferron, John R., Holcomb, Christopher T., Humphreys, David A., Liu, Feng, Luce, Timothy C., Park, Jin Myung, Prater, Ronald, Turco, Francesca, & Walker, Michael L.. Combined magnetic and kinetic control of advanced tokamak steady state scenarios based on semi-empirical modelling. United States. doi:10.1088/0029-5515/55/6/063011.
Moreau, Didier, Artaud, J. F., Ferron, John R., Holcomb, Christopher T., Humphreys, David A., Liu, Feng, Luce, Timothy C., Park, Jin Myung, Prater, Ronald, Turco, Francesca, and Walker, Michael L.. 2015. "Combined magnetic and kinetic control of advanced tokamak steady state scenarios based on semi-empirical modelling". United States. doi:10.1088/0029-5515/55/6/063011. https://www.osti.gov/servlets/purl/1375957.
@article{osti_1375957,
title = {Combined magnetic and kinetic control of advanced tokamak steady state scenarios based on semi-empirical modelling},
author = {Moreau, Didier and Artaud, J. F. and Ferron, John R. and Holcomb, Christopher T. and Humphreys, David A. and Liu, Feng and Luce, Timothy C. and Park, Jin Myung and Prater, Ronald and Turco, Francesca and Walker, Michael L.},
abstractNote = {Our paper shows that semi-empirical data-driven models based on a two-time-scale approximation for the magnetic and kinetic control of advanced tokamak (AT) scenarios can be advantageously identified from simulated rather than real data, and used for control design. The method is applied to the combined control of the safety factor profile, q(x), and normalized pressure parameter, beta(N), using DIII-D parameters and actuators (on-axis co-current neutral beam injection (NBI) power, off-axis co-current NBI power, electron cyclotron current drive power, and ohmic coil). The approximate plasma response model was identified from simulated open-loop data obtained using a rapidly converging plasma transport code, METIS, which includes an MHD equilibrium and current diffusion solver, and combines plasma transport nonlinearity with 0D scaling laws and 1.5D ordinary differential equations. The paper discusses the results of closed-loop METIS simulations, using the near-optimal ARTAEMIS control algorithm (MoreauDet al 2013 Nucl. Fusion 53 063020) for steady stateAT operation. With feedforward plus feedback control, the steady state target q-profile and beta(N) are satisfactorily tracked with a time scale of about 10 s, despite large disturbances applied to the feedforward powers and plasma parameters. We also show the robustness of the control algorithm with respect to disturbances of the H&CD actuators and of plasma parameters such as the H-factor, plasma density and effective charge.},
doi = {10.1088/0029-5515/55/6/063011},
journal = {Nuclear Fusion},
number = 6,
volume = 55,
place = {United States},
year = {2015},
month = {5}
}