End loss measurement of neutral-beam-injected field-reversed configuration plasma

End loss flux measurements have been performed by using ion energy analyzer in order to investigate the confinement improvement in a field-reversed configuration (FRC) plasma sustained by neutral beam injection (NBI). The experimental results show that the energy confinement time of FRC has been extended by about 100% compared with the no NBI case. To understand these experimental phenomena, some measurements have been performed on end loss flux. Previous theoretical studies predict injected hot beam ion walls would play a role in improving the confinements on the edge layer by some electrostatic effects. However, significant evidences suggesting these electrostatic effects on the edge layer due to NBI have never been observed in this work. (author)