Single shot photographic spectra of hydrogen‐like aluminum Lyman series lines are obtained from a low inductance vacuum spark. Corresponding pinhole pictures yield information on the source size. The observed line profiles are found to increase in width along the series and the higher series membersL&ggr;andL&dgr;can be matched with convolved Stark and Gaussian profiles. The Gaussian profile includes the effects of source size, thermal Doppler broadening, and crystal resolution. The space and time‐averaged electron density determined from the profile analysis is 2.5×1021–1×1022cm−3.