Range Profiles of 300- and 475-eVHe+4Ions and the Diffusivity ofHe4in Tungsten

摘要: Range profiles for 300- and 475-eV $^{4}\mathrm{He}^{+}$ ions implanted in situ tungsten at 60, 61, 80, 90 K were measured, directly absolutely, employing an atom-probe field-ion microscope. A mean range ($\overline{x}$) of 40 \ifmmode\pm\else\textpm\fi{} 4 \AA{} a parent standard deviation ($\ensuremath{\sigma}$) 20 to 36 was obtained 300-eV $^{4}\mathrm{He}^{+}$; values $\overline{x}$ $\ensuremath{\sigma}$ 56 6 37 42 \AA{}, respectively, determined $^{4}\mathrm{He}^{+}$. The existence isolated immobile interstitial $^{4}\mathrm{He}$ atom established enthalpy change migration 0.24 0.32 eV determined.