ИСТИНА

A multi-element ultrasound array for generating high-intensity focused ultrasound (HIFU) in air in the low-frequency ultrasonic range has been developed and manufactured. The array elements are 128 piezoelectric transducers mounted on a spherical base with the ability to adjust their position. The operating frequency is 35.5 kHz, the source diameter and focal length are 0.5 m. The elements are installed close to each other, and their centers are located on 8 spirals to avoid periodicity and thereby suppress parasitic diffraction maxima. All array elements are electrically connected in parallel and excited by a signal from a power amplifier. To study the characteristics of the emitted ultrasound beam, the transient acoustic holography method was used. In addition to microphone measurements, an experiment was conducted to find the total acoustic power using the radiation force balance, during which the acoustic radiation force acting on a conical reflector was measured. Nonlinear propagation effects in the focused beam were modeled using the “HIFU beam” open-source software. It was shown experimentally and theoretically that the wave profile at the focus of the developed array contains developed shock fronts, and the achievable maximum acoustic pressure level is more than 175 dB. The work was supported by the Russian Science Foundation (project # 25-12-00141).