U/Fe multilayers were fabricated with the expectation that the magnetic anisotropy behaviour (perpendicular magnetization of the Fe layers) seen in analogous multilayers of Ce and Fe would occur also in these multilayers. This behaviour has not been observed and it is suspected that the reason is connected with the nature of the interfaces between the U and Fe layers. In this investigation Mössbauer spectra of a standard U/Fe multilayer are compared to those of samples that may reproduce the conditions of the interface. The results show that samples of co-sputtered U and Fe simulate reasonably well the interface spectra and that the non-magnetic Fe seen in this material would inhibit magnetism induced in the U layers via the adjacent Fe layers and hence explain the absence of the expected magnetic anisotropy in U/Fe multilayers.

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In the planar Doppler velocimetry (PDV) technique, a molecular/atomic filter is employed to convert frequency shifts in scattered light to intensity variations. The potential for instantaneous three-component velocity measurements over an entire laser sheet makes PDV attractive for use in large wind tunnels. The development and integration of hardware and software for deployment of a multi-component PDV system is reported. Hardware issues addressed include observation of the long-term stability of a starved iodine cell. In addition, the accuracy of the dot-locating scheme, essential in the PDV data-reduction process, is investigated using numerically generated images. Finally, operation of a two-component system is demonstrated with velocity measurements in a supersonic jet with a large-scale perturbation. Here, energy from a Nd:YAG laser is focused into the shear layer near the lip of the nozzle to create a small thermal spot. The PDV technique is then employed to study the evolution of the large-scale disturbance. Two orientations of the two-component velocity measurement system are used to produce phase-averaged three-component mean velocity measurements of the perturbed jet 170 and 220 µs after the introduction of the disturbance.