Analysis of neutron energy spectra from neutral beam heated plasmas in the JET tokamak

Abstract

Neutron energy spectra from deuterium neutral beam heated plasmas at the Joint European Torus (JET) have been measured with a time-of-flight spectrometer. The different source fractions, resulting from thermal-thermal (TT), beam-thermal (BT) and beam-beam (BB) interactions have been extracted. The measured TT fraction and associated ion temperature is checked for consistency with diagnostic data for electron density ne, effective charge Zeff, ion temperature Ti and total neutron emission. Two different ways of comparing the data are represented. Firstly, the measured TT fraction, total neutron emission, ne, Zeff and Te profile shape are used to deduce a consistent Ti, which is compared with Ti values obtained independently by other diagnostics. Secondly, the measured TT fraction, total neutron emission, ne profile shape and Ti are used to determine a consistent thermal deuterium density nD, which is compared with nD obtained from Zeff measurements.