Estimation Of Anisotropic Neutron Emission Spectrum Using Spatial Neutron Flux Profile Outside Vacuum Vessel

It is known that emission spectrum of fusion products is anisotropically distorted from Gaussian distribution when fuel ion velocity distribution function is anisotropic non-Maxwellian distribution. Previously, anisotropic neutron emission has been measured in experiments with the Large Helical Device (LHD). In this study, as an application, a method for evaluating anisotropic neutron emission spectra by measuring the spatial profiles of the neutron flux is presented. Assuming beam-heated deuterium plasma in a JT-60SA class tokamak device, it was confirmed that the effect of neutron flux emission appears in the neutron flux spatial profile outside the vacuum vessel when the energy region to be measured is set to the high energy side. In addition, it was shown that the characteristic change of the anisotropic emission spectrum is reflected in the spatial profile of the neutron flux. Estimating the neutron anisotropic emission spectrum by this measurement method can lead to new proposals for fast ion diagnosis such as analysis of velocity distribution functions. (C) 2021 The Japan Society of Plasma Science and Nuclear Fusion Research