Enhancement of Ne-like Ar 46.9 nm laser output by mixing appropriate He ratio at low pressure Y. P. Zhao, Y. Xie, Q. Wang and T. Liu Eur. Phys. J. D, 49 3 (2008) 379-382 Published online: 03 October 2008 DOI: 10.1140/epjd/e2008-00181-4