Adjoint Monte Carlo Simulation of Fusion Product Activation Probe Experiment in ASDEX Upgrade tokamak

摘要

The activation probe is a robust tool to measure flux of fusion products froma magnetically confined plasma. A carefully chosen solid sample is exposed tothe flux, and the impinging ions transmute the material making it radioactive.Ultra-low level gamma-ray spectroscopy is used post mortem to measure theactivity and, thus, the number of fusion products. This contribution presents the numerical analysis of the first measurement inthe ASDEX Upgrade tokamak, which was also the first experiment to measure asingle discharge. The ASCOT suite of codes was used to perform adjoint/reverseMonte Carlo calculations of the fusion products. The analysis facilitates, forthe first time, a comparison of numerical and experimental values forabsolutely calibrated flux. The results agree to within a factor of about two,which can be considered a quite good result considering the fact that allfeatures of the plasma cannot be accounted in the simulations. Also an alternative to the present probe orientation was studied. The resultssuggest that a better optimized orientation could measure the flux from asignificantly larger part of the plasma.