Neutron Energy Spectrum Measurements with a Compact Liquid Scintillation Detector on EAST

TL;DR

This paper describes the use of a liquid scintillation detector to measure neutron energy spectra in EAST fusion plasma, including detector characterization, shielding improvements, and plasma diagnostics.

Contribution

It introduces a compact liquid scintillation detector setup for neutron spectrum measurement at EAST and validates its performance through experiments and simulations.

Findings

Neutron spectra consistent with other measurement methods

Enhanced count rate with new shielding device

Plasma ion temperature deduced from neutron spectra

Abstract

A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and gamma-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI (Tl) gamma-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.