The ultrasonic power supply converts 50/60 Hz voltage to high frequency electrical energy. This electrical energy is transmitted to a piezoelectric transducer with the converter, where it is changed to mechanical vibrations. The ultrasonic vibrations are intensified by the probe and focused at the tip where the atomization takes place.

Every ultrasonic nozzle operates at a specific resonant frequency, which is determined primarily by the length of the nozzle. In order to produce standing, sinusoidal longitudinal waves, a necessity for the sustained vibration that produces atomization, the nozzle must be an integral number of half-wavelengths long. This requirement arises

because bath free ends of a nozzle must be anti-nodes; that is, points of maximum vibrational amplitude. Open-ended organ pipes and chimes are other examples of this type of wave motion.

Sonics nozzles are manufactured in two different frequencies: 20 and 40 kHz. To give a sense of the physical size of these nozzles, one wavelength at 20kHz is approximately 5”.

A 40kHz nozzle, one of the more common types in use, is approximately 2.5” long for the half-wavelength version.

There are several features worth noting. Probes / horns can only be mounted or clamped at the nodal point (point of no activity). For applications involving an interface to a  vacuum chamber or another type of chemical reaction chamber, the probe can be machined with a mounting flange that bolts to an existing port on the reactor.

All probes are fabricated from high-strength titanium alloy (Ti-6Al-4V). This alloy also exhibits exceptional resistance to chemical attack.

The probes shown above features a cone-shaped atomizing surface. Its purpose is to spread out the spray. Some applications require that the spray be very narrow. In those cases, the atomizing surface is sculptured into a flat or nearly flat surface. Depending on the width requirements of the spray pattern and the required flow rate, the atomizing surface may have a very small diameter or an extended, flat section.

The configuration on the left shows the cone-shape spray pattern resulting from the conical shaped atomizing surface. Typically a spray diameter from 2-3 inches can be achieved. The one in the middle is characteristic of Sonics microspray line of nozzles.

For this type of nozzle, the orifice size is from 0.015-0.040 inches. It is usually recommended for use in applications where very small amounts of material are to be delivered or where flow rates are very low. The one on the left depicts a cylindrical spray shape used in applications where the flow rate can be relatively high, but where the

lateral extent of the spray pattern must be limited.