Anomalous Hydrogen/Strontium Discharge

We report the observation of intense extreme ultraviolet (EUV) emission from incandescently heated atomic hydrogen and atomized strontium. Typically the emission of extreme ultraviolet light from hydrogen gas is achieved via a discharge at high voltage, a high power inductively coupled plasma, or a plasma created and heated to extreme temperatures by RF coupling (e.g. > 10 6 K) with confinement provided by a toroidal magnetic field. The observed plasma formed at low temperatures (e.g. ≈ 10 3 K) from atomic hydrogen generated at a tungsten filament that heated a titanium dissociator and atomic strontium which was vaporized from the metal by heating. No emission was observed when sodium, magnesium, or barium replaced strontium or with hydrogen or strontium alone. The power balance of a gas cell having atomized hydrogen and strontium was measured by integrating the total light output corrected for spectrometer system response and energy over the visible range. Control cell experiments were identical except that sodium, magnesium, or barium replaced strontium. In the case of hydrogen/sodium, hydrogen/magnesium, and hydrogen/barium mixtures, 4000, 7000, and 6500 times the power of the hydrogen/strontium mixture was required, respectively, in order to achieve that same optically measured light output power. A plasma formed at a cell voltage of about 250 V for hydrogen alone and sodium/hydrogen mixtures, and 140-150 V for hydrogen/magnesium and hydrogen/barium mixtures; whereas, a plasma formed for hydrogen/strontium mixtures at an extremely low voltage of about 2 V.