Simulation of Magnetic Measurements on the T-15MD Tokamak Taking into Account Eddy Currents in the Vacuum Chamber

In connection with the start-up of the T-15MD tokamak, testing of numerous magnetic probes of the electromagnetic diagnostic system is an important problem, because measurements from magnetic probes are used to control the plasma discharge. The article analyzes the first experiments on measuring the magnetic field performed on the T-15MD tokamak. A program has been created in which Kirchhoff equations for currents in poloidal coils and eddy currents in a vacuum chamber and passive stabilization conductors are solved. The distribution of the magnetic field and voltage in the magnetic probes are calculated and compared with experimentally measured values. As a result, it is found that some probes have incorrect connection polarity and that the signals from two probes are mixed up during recording to the database. It is shown that large currents are induced in the vacuum chamber, which will influence the plasma equilibrium, especially at the initial stage of current rise. An algorithm is proposed to improve the 2D model of the T-15MD chamber, which increases the accuracy of calculating the eddy currents and thereby improves plasma discharge control.