Design of inductive sensors and data acquisition system for diagnostics of magnetohydrodynamic instabilities on the T-15MD tokamak

Magnetic diagnostics plays an important role in tokamak operation. Magnetic data are used for the real-time control of plasma current, shape and position and for post-discharge analysis of magnetohydrodynamic (MHD) plasma instabilities and equilibrium reconstruction. The magnetic diagnostic of the T-15MD will consist of more than 350 inductive sensors of various types. Location and number of sensors is determined by the measured physical value. The data acquisition system must simultaneously provide both the real-time data transfer of some sensors to the control loop and all sensors data storage for subsequent analysis. The requirements for the data acquisition depend on the data destination. For the data transferred to the control loop is sufficient to have a sampling rate up to 10 kHz, but this data must be transferred and processed in real-time mode. At the same time, for the study of fast processes (disruptions, tearing modes, Alfven eigenmodes), sensor signals should be acquired with a sampling rate from 100 kHz to 2 MHz and transferred to the database in about 3 min after discharge. The article describes the construction and location of inductive sensors, as well as the peculiarity of the magnetic diagnostics data acquisition system.