Hard-Type Piezoelectric Materials Based Double-Parabolic-Reflectors Ultrasonic Transducer (DPLUS) for High-Power Ultrasound

To achieve wide-frequency (20 kHz-2 MHz) high-power output (10 MPa) of Double Parabolic refLectors wave-guided Ultrasonic tranSducers (DPLUS), this paper investigated the DPLUS with hard-type PZTs. Under resonant excitation of the DPLUS waveguide, around 30 harmonic longitudinal modes from the thin waveguide (1 mm in diameter and 40 mm long) can be excited between 20 kHz to 2 MHz. From 20 kHz to 0.4 MHz, the maximum peak vibration velocity was 7.5 m/s; from 1 MHz to 2 MHz, the maximum peak vibration velocity of hard-type PZT DPLUS (7 m/s) was 3.5 times of soft-type piezoelectric materials DPLUS (2 m/s). Acoustic evaluation revealed large acoustic pressure at a wide frequency range: 0.46 MPa (at 31 kHz), 10 MPa (at 590 kHz), 7.7 MPa (at 1.154 MHz), and 7.2 MPa (at 1.322 MHz). Results proved wide-frequency and high-power operation of DPLUS, which are significant for realizing various applications.