An Integrated Dual-Mode Pulse-Echo Ultrasonic Measurement System Under Pulsed/Static Magnetic Field

Ultrasonic measurements at high magnetic fields and low temperatures necessitate ultrafast excitations, ultrahigh dynamic range of duty-cycle adjustments, and real-time, precise, and automatic analysis. This article proposes a dual-mode ultrasonic measurement system, which means the capability of carrying out acoustic measurements in both pulsed and static high magnetic fields with low temperatures. Based on the “counter-delay-chain” series structure and adaptive jitter compensation in the field-programmable gate array (FPGA), the timing control accuracy of 5 ns and the timing jitter below 160 ps are realized for high-resolution excitation generation and precise sampling window adjustment. The duty cycle adjustment achieves a high dynamic range from 0.23 ppb to 10% to realize both pulsed field mode and static field mode (denoted as PF mode and SF mode) ultrasonic measurements. The independent sampling window adjustment reduces the data size by more than 80%, extends the maximum testing duration, and reduces the analysis consumption. Combined with the automatic cross-correlation analysis method, this system can automatically carry out PF-mode tests with a repetition rate above 100 kHz and SF-mode tests for hours with a sound velocity error of 2%. Experiments have proved the reliability and feasibility of the system and revealed its application prospect in condensed matter physics experiments. This integrated automated measurement system can flexibly switch measurement modes and control parameters, thus adapting to the diverse measurement needs of cutting-edge physics experiments and industrial fields.