Measurement of Stark Profiles of Neutral and Ionized Helium and Hydrogen Lines from Shock-Heated Plasmas in Electromagnetic T Tubes

The slab of plasma behind primary or reflected shock fronts served as thermal light source. Electron densities were determined from absolute continuum intensities. Temperatures in helium followed from intensity ratios of ion and neutral lines, or at lower temperatures and in hydrogen from relative line and continuum intensities. Line profiles were measured by scanning with monochromators from shot to shot. Experimental widths and shifts were compared with values calculated from measured electron densities and temperatures. For hydrogen (H_α, H_β, H_γ), neutral helium (5876, 5016, 4713, 4471, 3889, 3188A) and ionized helium (4686, 3203A), the widths agree within 10% with theory. He ii 4686A exhibits a blue-shift, probably due to the polarization of the plasma near the emitting ions. The measured shifts of the neutral helium lines tend to be smaller than the calculated values, and the agreement with calculated shifts is poorer than in case of the widths.