First Neutron Spectrometry Measurement at the HL-2A Tokamak

TL;DR

This paper introduces a compact liquid scintillator neutron spectrometer designed for the HL-2A tokamak, featuring digital pulse discrimination, high-rate data acquisition, and validated through simulations and measurements for plasma neutron analysis.

Contribution

The paper presents the first neutron spectrometry measurement at HL-2A using a novel digital liquid scintillator spectrometer with comprehensive characterization and simulation validation.

Findings

Good agreement between simulated and measured pulse height spectra.

Effective radiation and magnetic shielding implemented.

Spectrometer suitable for studying plasma heating and fast-ion phenomena.

Abstract

A compact neutron spectrometer based on the liquid scintillator is presented for neutron energy spectrum measurements at the HL-2A tokamak. The spectrometer was well characterized and a fast digital pulse shape discrimination software was developed using the charge comparison method. A digitizer data acquisition system with a maximum frequency of 1 MHz can work under an environment with a high count rate at HL-2A tokamak. Specific radiation and magnetic shielding for the spectrometer were designed for the neutron spectrum measurement at the HL-2A tokamak. For pulse height spectrum analysis, dedicated numerical simulation utilizing NUBEAM combined with GENESIS was performed to obtain the neutron energy spectrum. Subsequently, the transportation process from the plasma to the detector was evaluated with Monte Carlo calculations. The distorted neutron energy spectrum was folded with the response matrix of the liquid scintillation spectrometer, and good consistency was found between the simulated and measured pulse height spectra. This neutron spectrometer based on a digital acquisition system could be well adopted for the investigation of the auxiliary heating behavior and the fast-ion related phenomenon on different tokamak devices.