The role of neutron measurements in the study of burning fusion plasmas

The use of neutron measurments for diagnosing the plasmas of present and next generation tokamaks is discussed. The diagnosis of these high reactivity fusion plasmas can be expected to be crucially dependent on neutron based information. The measurements that can be made to determine main plasma parameters directly and some of the plasma information that can be deduced from neutron data are reviewed. Especially, we discuss the neutron measurements that can provide information on the behavior of fast ions, which is of relevance for understanding the production, transport and heating of α-particles, as well as on the plasma conditions produced by large fast ion components. (author)