Experiments on D-T neutron source characteristics of an FNS high speed water cooled target

The D-T neutron source is essential for the fusion neutronics experiments and it is of importance to characterize the source conditions in order to perform the experiment as well as analysis with high accuracy. A fast water cooled D-T target system at the end of the 80deg beam line of FNS accelerator was installed for the fusion blanket integral experiments. The target assembly has a rather complex and tight structure in order to reduce high heat production due to high incident d+ beam current at the target position. It is expected that the target structure influences the neutron spectrum and angular distributions of the neutrons emitted from the assembly. Prior to successive blanket neutronics experiments, measurements have been carried out on the source characteristics. The angular distribution of the neutron fluxes on horizontal, vertical and axial planes were measured with the foil activation technique. The angular distribution was also measured by an NE213 scintillation counter using a dual rotatable deck. The angles dependent neutron spectra around the target were obtained with TOF technique. Experimental results were discussed on the basis of the nuclear reaction kinematics for 3T(d,n)4He by taking the target structure into account. As a result, it was proved that the structure of the assembly affects significantly the neutron emission character. The experimental data obtained will be used for verification of analytical calculation of D-T source. (author)