The First Experimental Results of Time-of-Flight Neutron Spectrometer at EAST

Neutron emission spectroscopy (NES) measurements at Experimental Advanced Superconducting Tokamak (EAST) are described. Both measurements and simulations of the neutron energy spectrum were done for the NBI-heated plasma at EAST. The experimental results were measured by the time-of-flight (TOF) neutron spectrometer TOFED, which was moved outside the experimental hall and installed in the newly-built nuclear diagnostics laboratory. A fully digital data acquisition system based on the digitizers was designed and utilized for the TOFED, which satisfied all the primary scintillators and 16 secondary scintillators. The TOFED prototype firstly obtained the neutron time-of-flight spectra with optimized signal-to-noise ratio in the 2017 EAST experiment campaign, when the NBI heating systems were employed. The neutron time-of-flight spectra were distinctly broadened, compared to the simulation of neutron spectra from the thermal plasma with the code GENESIS. These experimental results demonstrate the capability of the time-of-flight neutron spectrometer TOFED to contribute to the studies on fast ion physics at EAST.