2021 Volume 16 Pages 1402039
Characteristics of the new vertical neutron camera (VNC3) installed for the study of energetic-particle transport in the relatively low neutron emission rate (Sn) in Large Helical Device (LHD) deuterium plasma is investigated. Dependence of signal of VNC3 operating with the current mode on Sn shows that accurate neutron signal is obtained using VNC3 in low Sn range with 10ms time bin where the error of neutron counts of first vertical neutron camera (VNC1) operating with the pulse counting mode is significantly large. Time-resolved measurements of neutron emission profiles in deuterium beam heated low Sn plasmas are performed. Although the line-integrated neutron obtained by VNC3 is wider due to its larger inner diameter of the collimator compared to VNC1, the neutron profile measured by VNC3 is almost matched with the neutron profile measured by VNC1. The time-resolved neutron profile measurement in low Sn discharge with relatively short time period becomes possible using VNC3.
