A model for calculating neutral helium radiation for the Globus-M2 tokamak peripheral plasma spectroscopic diagnostics

A simple model has been developed for calculating synthetic images of neutral helium clouds recorded by spectroscopic diagnostics of peripheral distributions of electron temperature and concentration at the Globus-M2 tokamak. The size of the numerically obtained radiating helium cloud is in a quite good agreement with experimental results. Calculations of the effect of averaging the radiation intensity along the line of sight on the recovered electron temperature values demonstrate the need to reduce the angular broadening of the injected helium jet to 10–15$^\circ$; in this case, the relative measurement error will not exceed 10–20%. As a means for practical engineering implementation of such a helium jet, a Laval nozzle with a set of diaphragms is proposed.