[en] The energy spectra of ²³⁵U atoms sputtered from a 93% enriched ²³⁵U metal foil and a hot pressed ²³⁵UO pellet by an 80 kev ⁴⁰Ar⁺ beam were measured in the range 1 eV to 1 keV. The measurements were made using a mechanical time-of-flight spectrometer in conjunction with the fission track technique for detecting ²³⁵U. The design and construction of this spectrometer are discussed in detail, and its operation is mathematically analyzed. The results of the experiment are discussed in the context of the random collision cascade model of sputtering. The spectrum obtained by the sputtering of the ²³⁵U metal target was found to be well described by the functional form E(E+E/sub b/)^-277, where E/sub b/ = 5.4 eV. The ²³⁵UO₂ target produced a spectrum that peaked at a lower energy (approx. 2 eV) and decreased somewhat more rapidly for E approx. > 100 eV