Negative ions formed in N2/CH4/Ar discharge – A simulation of Titan's atmosphere chemistry G. Horvath, Y. Aranda-Gonzalvo, N. J. Mason, M. Zahoran and S. Matejcik Eur. Phys. J. Appl. Phys., 49 1 (2010) 13105 Published online: 26 November 2009 DOI: 10.1051/epjap/2009192