A sodium (Na) beam edge diagnostic

Abstract A fast (40–80 keV) neutral sodium (Na) beam is considered as advantageous alternative to the fast lithium (Li) beam installed at ASDEX Upgrade. Recently, a complete data set of all relevant plasma particles (electron, ions) – Na collisions has been compiled [1] and first experiments with a Na beam installed at ASDEX Upgrade have been carried out. A collisional radiative model is employed to calculate the beam attenuation in a plasma discharge as well as the occupation number of Na excited states (including n = 3, 4, 5s). Excellent agreement between modeled and measured Na I emission profiles is found, proving the validity of the compiled data set. Despite the lower velocity at the same acceleration voltage, beam penetration of Na as compared with Li is not significantly deteriorated. The influence of electron temperature ( T e ) and Z eff profiles on evaluated electron density ( n e ) profiles is analyzed.