Neutron Camera in Large Helical Device

Three sets of neutron cameras have been developed in Large Helical Device to measure the spatial profile of energetic particles, since deuterium-deuterium neutrons are mainly produced by the reaction of thermal deuteron and energetic deuteron. One of neutron cameras is based on a stilbene scintillation detector operating in the pulse-counting mode with pulse shape discrimination ability for medium to high neutron emission discharges. The other two neutron cameras are based on an EJ-401 fast neutron scintillator detector operated in the current mode for low to medium neutron emission discharges. Neutron cameras have been a powerful tool for understanding beam ion confinement as well as beam ion transport during the beam ion-driven magnetohydrodynamic instabilities. The development and details of the neutron cameras in the Large Helical Device are described.