Device for producing a standard ultrasonic field

A device for producing a standing ultrasonic field at a frequency f in a liquid, the device comprising:

• a substantially dimensionally stable vessel including an outside wall and a substantially circular-cylindrical interior, the vessel configured and arranged for receiving the liquid and the at least one oscillation element;
• a transducer array including at least one oscillation element and a vessel wall section of the vessel in the region of the at least one oscillation element, wherein the transducer array further includes at least one layer including the vessel wall section of the vessel in the region of the at least one oscillation element;
• wherein the at least one oscillation element is acoustically connected to the outside wall of the vessel and configured and arranged to be excitable at the frequency f,
• wherein the substantially circular-cylindrical interior is configured and arranged for receiving the liquid with an inner radius ro at least in the region of the oscillation element;
• and
• wherein the oscillation element has a mean thickness p and a width b in the direction orthogonal to a main axis of the interior, and the width b is not greater than the inner diameter 2ro, the oscillation element has at least one substantially flat lateral surface, and in that the oscillation element is acoustically connected via this one flat lateral surface to a substantially flat connection surface of the outside wall of the vessel in the region of the circular-cylindrical interior, wherein the connection surface is arranged parallel both to the main axis of the circular-cylindrical interior and to the oscillation element, wherein the width b of the oscillation element is in the range between (rP·p·vC/vP)1/2 and 4·(rP·p·vC/vP)1/2,
• wherein rP=ro+co applies, ro is the inner radius of the interior, co is the minimum wall thickness of the vessel wall section in the region of the oscillation element, and wherein vC is the sound velocity in the vessel wall section, and where vP is the sound velocity in the thickness direction in the oscillation element,
• wherein the thicknesses of the at least one layer of the transducer array is selected such that natural resonance frequencies fer of the transducer array to the desired frequency f of the ultrasonic field have distances which are greater than one fifth of the distance fer,1−fer,2, wherein fer,1 and fer,2 are the two closest natural resonance frequencies fer with respect to the frequency f.