Lecture: Measurements for Identification and Control of Tokamak Plasmas

prof. Michela Gelfusa


Tokamak plasmas of reactor relevance are open systems, kept well out of equilibrium by continuous injection of energy and matter. They are therefore affected by many instabilities interacting nonlinearly and so very difficult to identify and control. This course introduces the measurement techniques, called diagnostics, deployed on the major devices, to assess their quality and to implement real time control strategies. The diagnostics presented cover all the major measuring methods used in big physics experiments: interferometry, polarimetry, reflectometry, spectroscopy etc. The range of wavelengths covered by these diagnostics spans the interval from radiofrequencies to gamma rays, requiring a background covering microwaves, atomic and nuclear physics. Special attention is accorded to the detection of neutrons, since they are the ultimate indicators of the plasma performances. The main control strategies, based on some of the most fundamental diagnostics, are also presented and their performance assessed in detail.