Regenerative system for continuous measurement of internal friction and Young's modulus of alkali halide crystals

A regenerative drive system is described for kilohertz acoustic measurements in alkali halide crystals. In the system field effect transistors are used as gain control elements to keep the strain-amplitude of mechanical vibrations constant during experiments in which internal friction and modulus are changing. Discussion is given of the main features of the design of the equipment, its testing and calibration and its application to experiments involving effects of nuclear radiation on alkali halide crystals.