Application Cases

Experiment Name: Measurement of Bubble Collapse Velocity Based on Mie Scattering

Experimental Principle:
Single-bubble sonoluminescence is highly sensitive to factors such as liquid type, gas species, gas concentration in the liquid medium, liquid temperature, and driving frequency. If any of these factors falls outside the luminescence parameter range, even if a stable standing wave field exists within the resonant cavity, it is difficult to induce luminescence in the bubble.

Figure: Schematic Diagram of the Experimental Setup for Single-Bubble Sonoluminescence

Experimental Procedure:
A stable standing wave field is formed inside a liquid-filled resonant cavity. A bubble is then injected into this resonant cavity, allowing it to stably exist at the antinode of the standing wave field. At this location, the bubble undergoes periodic expansion, collapse, and luminescence in strict accordance with the acoustic driving frequency.

Testing Equipment:

• Signal generator

• ATA-8202 RF power amplifier: Its main function is to provide appropriate power to the spherical resonant cavity. It features 50Ω input/output impedance matching, can be used with an external signal source, and has a power output of 100W.

• Impedance analyzer: Used for impedance measurement and analysis of the water-filled spherical resonant cavity, with a measurement frequency range of 40Hz–110MHz.

• Impedance matching coil: Inductance range: 5.7–14.75mH. Based on the analysis results from the impedance analyzer, an inductance coil is wound unidirectionally around a magnetic core and used to match the inductive impedance of the spherical resonant cavity, ensuring that the imaginary part of the cavity's impedance is zero. This improves the electroacoustic conversion efficiency of the piezoelectric ceramic transducer.

  
  

Figure: Schematic Diagram of the Mie Scattering Measurement and Calibration Setup

Test Results:
A sinusoidal signal of appropriate frequency is set on the signal generator. This signal is amplified to a certain power level by the power amplifier and then fed into the impedance matching coil. The position of the magnetic core in the impedance matching coil is adjusted to cancel the inductive impedance of the spherical resonant cavity at this frequency. This enables a pair of symmetrically attached piezoelectric ceramic transducers to stably emit acoustic waves of a specific frequency into the liquid-filled resonant cavity, forming a stable standing wave field. A bubble is then injected into the resonant cavity using a syringe, allowing it to stably exist at the antinode of the standing wave. By adjusting the frequency on the signal generator, the power on the amplifier, and the position of the magnetic core in the impedance matching coil, stable luminescence of the bubble in the resonant cavity is achieved. Under this method, single-bubble sonoluminescence can remain stable for several hours without external interference.

Figure: Specifications of the ATA-8000 Series RF Power Amplifier