Simultaneous Closed-loop Control of the Current and Electron Temperature Profiles in the TCV Tokamak
American Control Conference
Chicago, Illinois, USA, July 1-3, 2015
| Abstract |
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Two key properties that are often used to define a plasma operating scenario in nuclear fusion tokamak devices are the current and electron temperature (Te) profiles due to their intimate relationship to plasma performance and stability. In the tokamak community, the current profile is typically specified in terms of the safety factor (q) profile or its inverse, the rotational transform (iota = 1/q) profile. The plasma poloidal magnetic flux and Te dynamics are governed by an infinite-dimensional, nonlinear, coupled, physics-based model that is described by the magnetic diffusion equation and the electron heat transport equation. In this work, an integrated feedback controller is designed to track target iota (proportional to the spatial gradient of the poloidal magnetic flux) and Te profiles by embedding these partial differential equation models into the control design process. The electron thermal conductivity profile is modeled as an uncertainty, and the controller is designed to be robust to an expected uncertainty range. The performance of the integrated iota + Te profile controller in the TCV tokamak is demonstrated through simulations with the simulation code RAPTOR by first tracking a nominal target, and then modulating the Te profile between equilibrium points while maintaining the iota profile in a stationary condition.