11 Shape of Atomic Lines Emitted by positive corona discharge N. Bonifaci, F. Aitken, H. Gharbi Tarchouna, G2Elab Grenoble, France V Atrazhev, Joint Institute for High Temperatures, Russia V.A. Shakhatov, Topchiev of Petrochemical Synthesis Institute, Russia J. Eloranta Department of Chemistry,California State University, USA K. von Haeften, Leicester University, Leicester, UK G Vermeulen, Institut Néel Grenoble, France

22 Corona discharge in dense helium Liquide Light emission Transport zone : E ~ kV/cm µ e and µ+ Ionization zone : E p ~ MV/cm Densities of the plasma particles (N e and N p ), Temperature, etc 2 Crucial importance for the modelling of plasmas produced by electric discharges I ~ µA, DC V ~ kV Applied power : mW gap distance~mm R p ~ µm Gas pressure ~ bar CCD Camera picture

Shape of atomic line 706 nm for different states of cryogenic Helium in a cell POSITIVENEGATIVE Plane e Plane He+