Measurements of electron density and Stark width of neutral helium lines in a helium arc plasma H. M. Gao, S. L. Ma, C. M. Xu and L. Wu Eur. Phys. J. D, 47 2 (2008) 191-196 Published online: 25 January 2008 DOI: 10.1140/epjd/e2008-00013-7