Measurement of neutron flux in the primary stage of EAST deuterium plasma experiment

摘要

Five channels of time-resolved neutron flux monitor system have accomplished construction by ~3He proportion counter and ~(235)U fission chamber. That was be used for study neutron emission behavior at the initial stage of deuterium plasma experiment on EAST tokamak. At the condition of ohmic discharge, more of photo-neutrons production with low density during the plasma current ramp-up stage. Just increase the central chord average of electron density over 2.0x 10~(19)m~(-3), photo-neutron could be availably elimination. The power of lower hybrid wave (LHW) feed-in plasma excess a threshold has ideal effective for reduce loop voltage and photo-neutron, which power strong enough and plasma background parameter higher case that more fusion neutron production. Flux monitor system detected plenty of fusion neutrons during the Ion-cyclotron resonance frequency (ICRF) valid heating plasma.