Interaction ultrasound-magnetic field: experimental setup and detection of the interaction current

In the presence of a magnetic field, the propagation of ultrasound in an electrolyte produce a bulk current density due to Lorentz force. The present study describes the experimental set-up used to detect the interaction current in vitro. The used model consisted of a rectangular block of agar gel. A focused transducer produced pulses (6 μs, 500 kHz) with a peak pressure up to 1.5 MPa. The magnetic field was applied using a purpose-build permanent magnet. The current was collected using two rectangular brass plates, parallel to the beam axis and placed on opposite sides of the gel block. The collected current was about 100 nA. The passage of the ultrasound pulse through the interfaces gel/surrounding medium produced clearly identified waveforms. The inverse filtering of the time signal enabled the 1-D reconstruction of the interfaces. The conclusion is that the interaction current is detectable and can potentially give rise to a new imaging modality