Influence of hot electrons on radiative properties of a helium plasma

We have studied anomalous line intensities in space resolved helium plasmas in different configurations of the MISTRAL-B plasma divertor simulator experiment. Spectral simulations show that the different experimental configurations differ from one another by the hot electron fraction which drives the observed anomalous large emission of the singlet line 1s2s 1S–1s5p 1P compared with the triplet lines 1s2p 3P–1snd 3D. Theoretical spectra analyses carried out with the recently developed non-Maxwellian SOPHIA code are in good agreement with the data and allowed one to identify non-Maxwellian signatures. Independently performed Langmuir probe measurements are in good agreement with the spectroscopic analysis.