| Most of the work done in the past on shock loaded LiF was done using quartz gauges. Due to the non-linear response of quartz gauges and to the two wave structure in shock loaded LiF, only the initial elastic jump could be analyzed accurately. Electromagnetic particle velocity (EMV) gauges, which respond linearly to the particle velocity, were used for this work. The material used was single crystal LiF with a magnesium ion concentration of 160 to 200 ppm. Experiments were performed using both single gauge and multiple gauge configurations. The material was impacted along the <100> direction at a calculated stress at impact of 29.7 kbar.;The multiple EMV gauge configuration was not entirely successful due to the effects of the glue bonds. These effects were attenuation of the precursor amplitude, rounding of the precursor peak, an increase in the shock rise time, and an increase of the value of the stress minimum following the precursor. These effects appear to be due primarily to reflections at the LiF-glue interfaces rather than to absorption in the glue bond itself. The magnitude of the glue bond effect is strongly dependent on the time rate of change of the incident wave, with rapidly varing features of the wave being affected the most. A model is derived by which, in principle, the effects of the glue bond can be calculated and corrections made for them. Some ideas for improving the multiple gauge method in single crystal materials are discussed.;The single EMV gauge configuration was successful and permitted measurements of both the incident wave and of the wave reflected from the rear surface of the sample. This reflected wave showed a two wave structure very similar to the incident wave. From these measurements, the stress in the plastic wave was calculated to be 27 kbar and the dynamic yield strength was found to be 4 kbar. |
