Extreme ultraviolet spectroscopy of helium–hydrogen plasma

Abstract

Extreme ultraviolet spectroscopy was recorded on microwave discharges of helium with 2% hydrogen. Novel emission lines were observed with energies of q . 13.6 eV, q = 1, 2, 3, 7, 9, 11, or q . 13.6 eV, q = 4, 6, 8 less 21.2 eV corresponding to inelastic scattering of these photons by helium atoms due to excitation of He (1s2) to He (1s12p1). The average hydrogen atom temperature was measured to be 180–210 eV versus ≈3 eV for pure hydrogen. The electron temperature Te for helium–hydrogen was 30 500 ± 5% K compared to 7400±5% K for pure helium. Known explanations for the novel series of spectral lines and extraordinary broadening were ruled out.