Design of infrared radiation diagnostic calorimeter for the prototype radio frequency driven negative ion source for neutral beam injection

In order to study the generation and extraction of negative ions for neutral beam injection application, a prototype RF-driven negative ion source and the corresponding test bed are under construction at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The target of the negative ion source is extracting a negation ion beam of 350 A/m2 for 3600 s plasma duration and 100 s beam duration. According to the design parameters of test bed, the design of active cooling IR diagnostic calorimeter for testing beam characteristics is put forward. In order to increase the spatial resolution, the calorimeter adopts the block structure. The calorimeter is made up of 8×28 molybdenum hexahedron blocks, the gap between the neighboring blocks is 2 mm, and the size of each block is 18×18×30 mm3. In order to prolong the operation times, a copper cooling channel with a diameter of 10 mm is welded in the block. The thermal performance of calorimeter is assessed using FEM (Finite Element Method) for validating the feasibility of this design scheme. Mathematical simulation results show that the design can achieve to operate stably at the thermal flux 6.45MW/m2 and meet the requirement of beam diagnosis fully.