Extended scintillator-based fast-ion loss diagnostic in the EAST

A scintillator-based fast-ion loss detector (FILD) with a fast camera acquisition system has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can simultaneously measure the energy and pitch angle of the escaped fast ions in the scintillator plane. With the development of high-power external heating systems, the FILD system has been developed and upgraded with a photomultiplier tube (PMT) system to improve the temporal resolution to study fast-ion behaviors during neutral beam injection (NBI) heating and under resonant magnetic perturbation (RMP) discharge conditions. Photon imaging on the scintillator is divided into two parts by an optical splitter; one part is transferred to the fast charge-coupled device (CCD) system, and the other is transmitted to the PMT through an array of fibers. The FILD system is upgraded with a 25-channel (5 × 5) PMT (Hamamatsu Photonics, type no. H10492-003) array and a data acquisition system with a sampling rate of 2 MHz per channel. Preliminary experimental results show that the magnetic resonance perturbation affects the fast-ion losses. This paper presents the extended PMT acquisition system and the initial results of the FILD diagnostic relating to prompt losses, and the beam ion losses due to RMP are discussed.