Design of a neutron camera for the HL-2A tokamak

A new neutron camera, comprising nine individual photo-multiplier tubes coupled with liquid scintillators through light guides, was designed, constructed and installed on the HL-2A tokamak. Using the HL-2A tokamak as an example, the basic principles for designing a camera system in low fusion power tokamaks were illustrated in this paper. The 2"$\times$2" BC501A liquid scintillation detectors coupled with the gain stabilization system, were developed for neutron measurements and applied on the tokamak. A magnetic shielding system was designed, using the finite element method (FEM), to ensure excellent operation of detectors under a strong magnetic field. Energy calibration has been conducted and the light output function was compared with the PTB's values. The reasons for discrepancy and variations in the results are analyzed and discussed in detail in the paper.