An assembly consisting of a booster body and (usually) a booster clamp ring. A booster is placed between a transducer and horn in order to change the horn's amplitude and/or as a means of supporting the resonator stack. The nominal resonant frequency of the booster is the same as the nominal resonant frequency of the stack in which it is used.

Boosters are often color coded by anodizing to indicate the nominal gain. However, the gain may only be nominal. The following are used by several manufacturers —

Color Gain
Blue 0.5
Purple 0.6
Green 1.0
Gold 1.5
Silver 2.0
Black 2.5


Array of ultrasonic boosters
Figure 1. Array of boosters
(Courtesy of Sonics & Materials, Inc.)