Tokamak plasma magnetic control system simulation with reconstruction code in feedback based on experimental data

Abstract

In modern vertically elongated tokamaks it is critically important to maintain plasma near the first wall at the diverter phase of a plasma scenario. The reason for this is to allow plasma equilibrium reconstruction in real time, based on the external magnetic measurements of the plasma. This paper suggests a simulation approach to obtain plasma position, current, and shape control, with a plasma equilibrium reconstruction code used in feedback. The new basic idea of such a simulation is to combine scenario signals with the data coming from the linear model based on tokamak experimental data. This sum comes to the reconstruction code, which reconstructs the separatrix location and gaps between the tokamak first wall and the separatrix itself. Using the example of the functioning spherical tokamak Globus-M (Ioffe Institute, S-Petersburg, Russia), we show the results of simulation of plasma gaps in a closed-loop control system with an original H ∞ LPV plasma shape controller at upper X-point of the plasma magnetic configuration. The simulation approach may be applied to any tokamak elongated in the vertical direction to adjust plasma shape control systems before application in experiments.