Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1
    Electronic Resource
    Electronic Resource
    Electron field emission from intentionally introduced particles on extended niobium surfaces (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 3851-3860 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Field emission properties of microscopic particles of graphite, sulfur, and MoS2 deposited on nonemitting Nb surfaces under ultrahigh vacuum conditions are described. Both graphite and MoS2 particles are shown to emit strongly, with field enhancement factors of the order of 100, in contrast to sulfur particles, which emit only weakly. The emission characteristics are measured locally on the individual sites, and emitting particles are further characterized by microfocus Auger spectroscopy and scanning electron microscopy. Their behavior upon heat treatment was studied, with the main result that both for graphite and MoS2 particles the emission disappears after heating to 1200 °C. The properties of the artificially created emitters are compared with those of naturally occurring field emitters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336727
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Field emission from broad-area niobium cathodes: Effects of high-temperature treatment (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 892-901 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results made with a new apparatus for the study of localized field emission (FE) sites on broad-area cathodes. The apparatus is centered around a UHV field emission scanning microscope, consisting of a micromanipulator allowing precision cathode motion, a rotatable holder for broad and microtip anodes, and a fast high-voltage regulator allowing constant-current measurement of a distribution of both weakly and strongly emitting sites. Also included are an in situ scanning electron microscope, and a facility for in situ microfocus Auger analysis as well as scanning Auger microscopy. Samples can be high-temperature annealed without removal from UHV. These tools have been used to study the effects of heat treatment (HT) up to 2000 °C on the FE from nonanodized and anodized Nb cathodes. We find that HT at 800–900 °C increases the density of field emitters at a given electric field. HT at T〉1000 °C reduces the density, while at T≥1400 °C a drastic decrease of the emission occurs. We have repeatedly obtained surfaces of cm2 size which do not emit at 100 MV/m. If such an emission-free surface is heat treated again at 800 °C, new emitters appear. Typically, the physical size of the field emitters is a few μm, although in some cases a larger particle was found and in others no feature was seen at 0.5-μm resolution. A large variety of elements is associated with these particles. We discuss in particular the nature and origin of three types of emitters: (1) sulfur containing particles, (2) carbon particles, both of which were identified as new emitters after a 800 °C HT, and (3) FE sites which are especially resistant against HT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336560
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Electron field emission from broad-area electrodes (1982)
    Springer
    Applied physics 28 (1982), S. 1-24 
    Details
    ISSN: 1432-0630
    Keywords: 79.70 ; 52.80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this review, measurements are surveyed for both dc and microwave electric fields. These show significant emission at applied fields typically 100 times smaller than those expected theoretically or measured experimentally for ideal microtip cathodes. Recent work is reviewed which studies on a microscopic scale this emission and the localized sites which produce it. Rather than forming sharp field enhancing projections, these sites often appear flat and are frequently associated with grain boundaries or insulating inclusions. Following an examination of various techniques for changing the emission of a given cathode, several theoretical models are considered which may explain some aspects of the observed emission characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617778
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Proximity electron tunneling spectroscopy. III. Electron-phonon coupling in the Nb-Zr system (1980)
    Springer
    Journal of low temperature physics 40 (1980), S. 419-440 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: The technique of McMillan-Rowell tunneling spectroscopy, extended by a method of proximity junctions to poorly oxidizing materials, is applied to study electron-phonon coupling in Nb1−x Zr x at x = 0.25, corresponding to the maximum T cin the Nb-Zr alloy system. The resulting α2 F(Ω) function provides λ = 1.3 for the alloy, and indicates that the primary benefit to superconductivity upon alloying arises from softening of the effective phonon spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119514
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Proximity electron tunneling spectroscopy. IV. Electron-phonon coupling and superconductivity of tantalum (1981)
    Springer
    Journal of low temperature physics 44 (1981), S. 89-118 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: An extensive superconducting electron tunneling study of Ta, using both a proximity method and an optimized conventional spectroscopy, is reported. The results for Ta confirm the electron-phonon origin of superconductivity in this element, and provide slightly improved superconducting parameters: λ =0.73 and Μph * = 0.11. The results from the PET and optimized conventional methods are in substantial agreement, although the proximity method appears to provide somewhat better resolution of structure in the Eliashberg function α2 F(E).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00115078
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...