A source for producing alkali ion beams for lowenergy surface scattering spectroscopies Rev. Sci. Instrum. 60, 730 (1989); 10.1063/1.1141009 Apparatus for lowenergy ion scattering spectroscopies: Imaging angular distributions and collecting angle resolved energy spectra Rev. Sci. Instrum. 57, 433 (1986); 10.1063/1.1138905Ultrahigh vacuum apparatus for combined lowenergy electron diffraction, Auger spectroscopy, MeV ion scattering, and nuclear microanalysis Rev. Sci. Instrum. 53, 797 (1982);We have designed and constructed an apparatus that combines hyperthermal energy ion scattering « lOOeV) with low-energy ion scattering (afewhundredeVtoseveralkeV). The URV scattering chamber possesses a full range of sample preparation and characterization capabilities, including LEED, Auger spectroscopy, a Kelvin probe for work function measurements, and facilities for gas or alkali-metal deposition. The differentially pumped beamline provides well-collimated, monoenergetic beams of gas or alkali-metal ions ranging in energy from < 10 e V to 10 ke V. To illustrate the qualitative changes in the scattering behavior observed over this range, we present experimental results for Na + scattered off the Cu ( 110) surface with the incident ion energy ranging from S6 e V to 4 ke V. We also show a comparison between 1 ke V K + and 1 ke V Ar+ scattered from the same surface.
We present the design and performance of an alkali ion source which is the injection stage of an ion beam system for surface scattering experiments in the range of 10 eV to 10 keV. In order to maximize emitter lifetimes, emphasis was placed on obtaining low phase space beams which minimize current losses in later stages of the optics. The source is based on a commercially available solid state β-eucryptite emitter, uses two stages of extraction for independent control of extracted current and final beam energy, and has a modified Pierce confinement electrode to control space charge spreading inside the source. Results of computer ray tracing are included to illustrate the operation of this source. Tests with K+ ions at 500 eV have produced beams which, in the range of 600–700 nA, were space-charge limited in transport through the remainder of the system. Beam currents measured more than 1 m downstream of the source are nearly independent of the emitter surface temperature over a range of 1023 to 1142 °C. Emitter lifetimes in excess of 200 h have been obtained. Using this source and our beamline optics, we have produced at the sample position low phase space beams ranging in energy from 10 eV to several kiloelectron volts.
Traditionally, a "low-energy" house has been one that used little energy for space heating. But space heating typically accounts for less than half of the energy used by new U.S. homes, and for low heating energy homes, space heating is often the third largest end use, behind water heating and appliances, and sometimes behind cooling. Low space heat done m o t identify a lowenergy house. To better understand the detenninants of a lowenergy house, we collected data on housing characteristics, incremental costs, and energy measurements from energy-efficient houses around the world and in a range of climates. We compare the energy required to provide thermal comfort as well as water heating, and other appliances.We do not have a single definition of a low-energy house, but through comparisons of actual buildings, we show how different definitions and quantitative indicators fail. In comparing the energy use of whole houses, weather normalization can be important, but for cases in which heating or cooling energy is surpassed by other end uses, other normalization methods must be used.
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