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Fusion Science and Technology
ANS members approve amendment adding YMG rep to board of directors
The American Nuclear Society will include a representative from the Young Members Group on its Board of Directors after ANS members voted this week overwhelmingly in favor of amending Article B6 of the ANS bylaws. The change was mandated by Objective Outcome 5 of the ANS Change Plan 2020.
To keep the number of directors at 16, the approved amendment decreased the number of non–U.S. resident directors from three to two.
Eugenio Schuster, Miroslav Krstic, George Tynan
Fusion Science and Technology | Volume 43 | Number 1 | January 2003 | Pages 18-37
Technical Paper | dx.doi.org/10.13182/FST03-A246
Articles are hosted by Taylor and Francis Online.
Control of plasma density and temperature magnitudes, as well as their profiles, are among the most fundamental problems in fusion reactors. Existing efforts on model-based control use control techniques for linear models. In this work, a zero-dimensional nonlinear model involving approximate conservation equations for the energy and the densities of the species was used to synthesize a nonlinear feedback controller for stabilizing the burn condition of a fusion reactor. The subignition case, where the modulation of auxiliary power and fueling rate are considered as control forces, and the ignition case, where the controlled injection of impurities is considered as an additional actuator, are treated separately.The model addresses the issue of the lag due to the finite time for the fresh fuel to diffuse into the plasma center. In this way we make our control system independent of the fueling system and the reactor can be fed either by pellet injection or by puffing. This imposed lag is treated using nonlinear backstepping.The nonlinear controller proposed guarantees a much larger region of attraction than the previous linear controllers. In addition, it is capable of rejecting perturbations in initial conditions leading to both thermal excursion and quenching, and its effectiveness does not depend on whether the operating point is an ignition or a subignition point.The controller designed ensures setpoint regulation for the energy and plasma parameter with robustness against uncertainties in the confinement times for different species. Hence, the controller can increase or decrease , modify the power, the temperature or the density, and go from a subignition to an ignition point and vice versa.