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@TECHREPORT{Schorn:135902,
      author       = {Schorn, Ralph P.},
      title        = {{U}ntersuchungen zur {Z}ersträubung von
                      {K}upfer/{L}ithium-{L}egierungen},
      volume       = {Juel-2367},
      number       = {JUEL-2367},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich, Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-135902, JUEL-2367},
      series       = {Berichte der Kernforschungsanlage Jülich},
      year         = {1990},
      note         = {Record converted from JUWEL: 18.07.2013},
      abstract     = {The sputtering behavior of a copper based alloy containing
                      17 $at-\%$ of lithium has been studied under fusion relevant
                      ion bombardment by D+, He', Ne+, and Ar+ with energies
                      between 0.1 keV and 6 keV and flux densities of up to 10'6
                      particles/cm2s. The main question was, whether surface
                      segregation of the lithium component can balance the losses
                      due to sputtering and evaporation, and whether this way a
                      protective lithium surface layer can be maintained under
                      high particle flux irradiation. To investigate
                      time-dependent sputtering phenomena, laser-induced
                      fluorescence spectroscopy (LIF) has been employed to detect
                      atoms emitted from the multicomponent material . With LIF,
                      velocity distributions and absolute densities of Cu and Li
                      have been measured, offering the possibility to calculate
                      absolute partial sputtering yields. At room temperature, the
                      alloy target showed almost no reduction of the Cu sputtering
                      yield under Argon bombardment, compared to pure copper.
                      Under light ion irradiation by D+ and He" reduction factors
                      of up to two have been observed. The surface composition was
                      deduced from measured velocity distributions of the two
                      constituents by assuming a Thompson-distribution and fitting
                      the resp. surface binding energies, as well as from the
                      reduction factor of the Cu sputtering. Under
                      Ar+-irradiation, the surface showed the same composition as
                      the bulk, while under bombardment by lighter ions the
                      lithium concentration increased to a maximum of about 50
                      $at-\%$ (D+) in the outmost atomic layer. A sufficient
                      protective lithium surface layer could be achieved at
                      elevated temperatures above 400°C by heating up the sample
                      for about two hours without ion irradiation. After a
                      subsequent deposition of roughly 10'9 Ar+/cm2 of 6 keV
                      energy, the thickness of the built-up layer has decreased
                      considerably. Losses of lithium atoms due to high-flux
                      sputtering dominate segregation also at elevated
                      temperatures, although the ion dose being necessary to
                      decrease the lithium surface content to its original value
                      has risen by about four orders of magnitude with respect to
                      room temperature. The use of the present Cu/Li-material
                      therefore seems useless in a continuously operating fusion
                      reactor. The alloy can only maintain a protective lithium
                      surface layer at elevated temperatures in a pulsed reactor
                      concept, if the plasma is operated with a limited
                      duty-cycle. Moreover, a relatively high rate of lithium
                      evaporation was measured at temperatures above 400°C, which
                      furthermore limits the application of Cu/Li-alloys in fusion
                      devices.},
      cin          = {IEF-4},
      ddc          = {530},
      cid          = {I:(DE-Juel1)VDB812},
      typ          = {PUB:(DE-HGF)29},
      url          = {https://juser.fz-juelich.de/record/135902},
}