Single-polar power supply of high frequency capacitive transducers for measurement

Abstract

It is possible to increase the sensitivity of capacitive ultrasonic transducers in three ways: increasing the capacitance of the transducer, increasing the polarizing and pulsed high-frequency voltage applied in the transducer cover, using modern methods of processing information packet pulses excited and received from the product. The increase in the capacity of the transducer is limited by the design capabilities of the transducer itself and the selection of the dielectric separating the plate from the surface of the electrically conductive testing object. Using modern methods of processing the received information significantly complicates and increases the cost of implementation of the device using a capacitive transducer. The most acceptable, at the moment, way to increase the sensitivity is to increase the power of high-frequency voltage supply generators provided that packet pulses are excited. The generator presented in the article allows to create pulsed peak voltages in low-capacitance transducers of more than 3 kV with frequencies up to 5 MHz with a duration of 1 period of the filling frequency and sounding frequencies up to 1 kHz. It was experimentally shown that using the prototype of a new generator, the amplitudes of the pulses transmitted through a steel sample 20 mm thick were obtained, the ratio of which to the noise amplitude received by the miniature piezoelectric transducer is 13 times. Using the developed powerful amplifier of voltage pulses will increase the amplitude of the pulses received from the transducer and repeatedly reflected in the product.