Feasibility Analysis of 1-D Carbon Material in Application of Negative Particle Beam Diagnostics

An important feature of the China Fusion Engineering Test Reactor (CFETR) project is the additional heating obtained from the injection of neutral beams based on accelerated negative ions. For the neutral beams based on negative ions, the most important measurements are beam uniformity, beamlet divergence, and stripping losses. According to the CFETR requirement, the maximum allowed beam divergence angle and beam nonuniformity are 6 mrads and ±10%, respectively. As one-dimensional (1-D) carbon tiles have large ratio between perpendicular conductivity and parallel conductivity and high stability, they can be used for beam uniformity and beamlet divergence measurement. This paper investigates the influence on the response of 1-D carbon tile having the thermal characteristics and features of some dedicated diagnostics. Simulations show that it will be possible to verify experimentally whether the beam meets the requirement about the maximum allowed value. This work lays a foundation for design and application of high-precision beam diagnostic targets.