Investigation Of Fusion Neutron Diagnostic Technology On EAST Device

The energy of fusion reaction is mostly carried by neutrons which never suffer magnetic field confinement and possess strong penetrating capacity.Neutron will been come a research focus on exploit and utilize of magnetic confinement fusion energy and radioprotection.Measurement of neutrons not only provide information about fusion reaction and radioprotection of the plasma,but also can be used to fast ion transport,energetic particle stimulate instability and auxiliary heating mechanism research.The EAST(Experimental Advanced Superconducting Tokamak)device is mainly discharge operation with deuterium plasma and the DD fusion neutron yield higher to 10-15n/s(design value).Development neutron diagnostic systems to measurement neutron yield,emission rate distribution and spectrum that is very important for auxiliary heating and fast ion transport research during higher parameter operation on EAST.The thesis main works is execution around with the neutron diagnostics system design,integrating development,calibration test and data processing.According to EAST device operating parameter and the calculation results of neutron flux rate distribution,we have design four set of neutron flux monitor(NFM),six channels of radial neutron camera(RNC)and one set neutron energy spectrometer systems(NES).The time evolution neutron flux monitor system adopt 235U fission chamber and 3He proportional counter detectors combination design for satisfy the measurement demand of neutron yield across six orders of magnitude dynamic range on EAST device.The neutron camera employ six liquid scintillator which are collimated by a polyethylene and lead consisted shield to measurement the neutron emission rate spatial distribution on the upper half plane of plasma.The compact neutron spectrometer utilize a BC-501A liquid scintillator that depend on recoil proton method to measurement the DD fusion neutron energy distribution in the plasma core region.Those measurement systems of NFM,RNC and NES have accomplished hardware and software embedded integration on EAST that consider the device windows flange and peripheral space layout and agree with the interface protocol of central control communication and data acquisition.The application control software of higher speed digitizer and the pulse signals analysis codes(Pulse Shape Discrimination PSD,Pulse Higher Analysis PHA,Division Time Counting DTC)are rely on LabVIEW and MATLAB platform to independent development,and the neutron measurement achievement nuclear pulse signals full digitizing acquisition and procession.Absolute detection efficiency of neutron flux detector,each channels relative detection efficiency of camera and the channel address and recoil proton response of liquid spectrometer are calibrated by electrostatic accelerator and isotope radioactive source(Am-Be,252Cf,137Cs,2 Na).The campbelling mode and counting mode of NFM data acquisition are cross equivalent calibrated by DD fusion neutrons from EAST plasma.Moreover,application the multi-arthrosis mechanic arm of remote control carry a 252Cf source in EAST device vacuum vessel to performing neutron in-situ calibration experiment.Those various calibration results have been used in neutron diagnostic data process and analysis.Time-resolved of fusion neutron total yield can be obtained through with neutron flux data calculation.The fusion neutron emission rate spatial distribution have been acquisition by handle camera signals with PSD,PHA and DTC.Liquid scintillator obtain recoil proton pulse amplitude spectrum need unfold by inverse solution code(MXD MC32,GRV MC32)to get DD neutron energy spectrum.These neutron diagnostic systems achieve desired goal and obtain a lots of value data after them operate in EAST discharge experiment.In ICRF minority hydrogen(MH)heating mode,the ion temperature in plasma core region have obtained thought by total neutron yield and energy spectrum analysis respectively that compare with XCS measurement results exist deviation approximate 15%.The scaling law of neutron yield relation with ICRF coupling power and plasma current have been induction on this heating condition that is Sn = 2.6 × 1012 · PRF1.48·IP2.51.Implement NBI short pulse injection experiment(blips)and obtained the fusion neutron decay time is ?n_ex? 11.4 ms during 1#NBI left source injection,further calculation the electron collision slowing time is ?se ? 55.7 ms.The experimental phenomenon of neutron yield decrease due to energetic particle stimulation instability have been observed during NBI higher power heating.Compare the time-resolved of the neutron yield and profile between with NBI same direction and reverse direction injecting scenario and discovery the beam ions loss is more serious on reverse direction injecting.