Ultrasonic generation using a plasma igniter

This paper describes some preliminary results of the ultrasonic generation characteristics of a new ultrasonic transducer, the plasma igniter. Epicent ral out-of-plane responses have been measured using a wide bandwidth stabil ized Michelson interferometer. An electromagnetic acoustic transducer (EMAT ) has been used to measure the longitudinal wave directivity pattern genera ted by the plasma source and it compares well to those previously published for laser generated ultrasound. The fields of application of the plasma ig niter ultrasonic generation source are limited for reasons that will be exp lained, but its relatively low cost means that it does merit consideration in some cases.