Optimal MSE polarisation angle and q-profile estimation using Kalman filters and the plasma simulator RAPTOR

Abstract

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First demonstration of real-time kinetic equilibrium reconstruction on TCV by coupling LIUQE and RAPTOR

“…In the present paper we did not close the loop with the real-time controllers yet. However, the difference between the ι profile between LIUQE and RAPTOR observed in [27] is now resolved thanks to the achieved KER. Moreover, the RAPTOR results depend on the geometrical coefficients given by LIUQE which non-linearly depend on the ι profile of the latter.…”

“…In other tokamaks these diagnostics are used to constrain the equilibrium solution directly, also in real-time as in [7, 13-15, 53, 54]. In principle, real-time MSE measurements can also be included in RAPTOR with the EKF technique as described in [27]. We favour this approach when eventually porting this tool to other tokamaks that have real-time MSE measurements.…”

“…All the tools listed above have been developed to perform analysis after the experiments, however, in order to reliably achieve and maintain the performances required for future tokamaks such as ITER, real-time control of the kinetic and current density profiles, as well as the plasma equilibrium, will be needed [26,27]. Not only control algorithms, but also supervisory control functions such as real-time plasma monitoring for disruption avoidance rely on the quality of the reconstruction of the plasma state [28].…”

Application of the Ensemble Kalman Smoother to Turbulent Transport Analysis in LHD Plasma

“…Data assimilation methods can simultaneously estimate more than one parameter, or variable having its own uncertainty, and any variables connected with observed variables in a simulation model. Similar techniques based on Kalman filters have been applied for the safety factor profile estimation of tokamak plasmas [5]. The extended Kalman filter, which has been employed in Ref.…”

“…The extended Kalman filter, which has been employed in Ref. [5], needs a linear approximation of the system model and does not always work well for nonlinear system models. The data assimilation method, which assimilates both past and future data, has not yet been implemented.…”