Neutron emission spectrometer in magnetic confinement fusion

Abstract Comprehensive neutron diagnostics have been developed and used to study magnetic confinement fusion plasmas. The neutron emission spectrometer is one of the most powerful tools for understanding fusion plasma physics. Neutron spectroscopy was originally developed to measure the fuel ion temperature in thermal plasmas. With the advent of fast ion heating, the role of neutron spectroscopy has evolved to deepen the understanding of fast ion confinement. Since neutrons are primarily produced by the fusion reaction between the bulk ion and the fast ion, the neutron energy carries information about the fast ion energy. The details of neutron emission spectrometers, i.e., time-of-flight spectrometer, magnetic proton recoil spectrometer, and compact neutron emission spectrometer, as well as representative results of neutron spectrometry in Large Helical Device are reviewed.