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

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 \boldsymbolE // \boldsymbolB NPA is to measure the distribution function of fast ions in the HL-2A/3 tokamak. The \boldsymbolE // \boldsymbolB 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. The results of the simulations and beam tests for the stripping chamber are presented. 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 using a 50 kV electron cyclotron resonance ion source (ECRIS) platform. The detection unit consists of 32 lutetium-yttrium oxyorthosilicate (LYSO) detector modules arranged in two rows. The response functions of \alpha, hydrogen ions ( \mathrmH^+ , \mathrmH^+_2 and \mathrmH^+_3) and \gamma for a detector module were measured with ^241Am, ^137Cs and ^152Eu sources together with the 50 kV ECRIS platform. The overall results indicate that the designed \boldsymbolE // \boldsymbolB NPA device is capable of measuring the intensity of neutral hydrogen and deuteron atoms with energy higher than 20 keV.