Development of a real-time digital pulse acquisition and processing algorithm for compact neutron spectrometer on EAST

Neutron emission spectroscopy (NES) diagnosis is an important technique in high-power thermonuclear fusion experiments for studying fast ions. In the fusion NES measurement on the Experimental Advanced Superconducting Tokamak (EAST), the liquid scintillator detector was employed. This selection was based on the detector's high sensitivity, fast time-response and superior n-gamma discrimination properties. In order to meet the demands of high-parameter experiments and fully leverage the diagnostic capabilities, a new signal acquisition and processing (SAQP) system based on Micro-telecommunications computing architecture (MTCA) was developed equipped with real-time processing capabilities. The new SAQP system aims to perform real-time acquisition, processing and storage of neutron and gamma flux data from the NES system, allowing the possibility of maximum count rates of 2 Mcps during the EAST experiment. This paper presents the real-time algorithm implemented on field programmable gate array (FPGA). It possesses the capability for real-time baseline restoration, n-gamma discrimination, pulse amplitude analysis, pile-up event detection and dynamic pulse recording window for recording entire pulse waveforms. The new SAQP system, including the integrated real-time algorithm, underwent detailed testing with both a signal generator and a neutron generator. The experimental results indicate that the real-time algorithm successfully achieve all expected functions, enhancing performance in n-gamma discrimination and dynamically recording entire pulse waveforms at high count rates without data loss.