Ultrasonic instrumentation for measurements in high magnetic fields. II. Pulsed magnetic fields

We describe two state-of-the-art ultrasonic interferometers designed for pulse-echo ultrasound measurements in the short-pulse (40 ms) and intermediate-pulse (400 ms) 60 T magnets of the National High Magnetic Field Laboratory facilities at Los Alamos, NM. One interferometer utilizes a more commonly used scheme which has been adapted for a pulsed field environment. The second interferometer exploits digital processing of the undetected signal: the ultrasonic signal is digitized, stored in a computer, and later, analyzed.