Equipment for measuring plasma parameters such as density, temperature, fusion neutrons or magnetic field. For the control of thermonuclear fusion, it is essential to obtain maximum information about the plasma properties and their evolution in time. This is done by various types of equipment, collectively referred to as diagnostics, which use a wide range of direct and indirect measurement methods. For example, the density, temperature, shape and strength of the magnetic field, the current through the plasma, the chemical composition of the plasma, the presence of fusion neutrons, or the electromagnetic radiation from the plasma are detected. The data obtained allow, on the one hand, to understand the processes in the plasma, to refine theories or models of the fusion plasma and, last but not least, to control the discharge so that fusion can take place successfully in the plasma.