The research progress of an E//B neutral particle analyzer

Abstract

An E//B neutral particle analyzer (NPA) has been designed and is under development at Sichuan
University and Southwestern Institute of Physics. The main purpose of the E//B NPA is to measure the
distribution function of fast ions on HL-2A/M tokamak. The E//B NPA contains three main units, i.e.
the stripping unit, the analyzing unit and the detection unit. A gas stripping chamber was adopted as
the stripping unit. Results of the simulations and beam tests for the stripping chamber are presented.
The parallel electric and magnetic fields provided by a NdFeB permanent magnet and two parallel
electric plates were designed and constructed for the analyzing unit. The calibration of the magnetic
and electric fields was performed at the 50 kV electron cyclotron resonance ion source (ECRIS)
platform. The detection unit consists of 32 LYSO detector modules arranged in 2 rows. The response
functions of α, hydrogen ions (H+, H+2 and H+3 ) and γ for a detector module were measured with
241Am, 137Cs and 152Eu sources together with the 50 kV ECRIS platform. Overall results indicate that
the designed E//B NPA device is capable to measure the intensity of neutral hydrogen and deuteron atoms with energy higher than 20 keV.