Ultrasonic surgical instruments

A surgical instrument, comprising:

• a transducer configured to provide vibrations along a longitudinal axis at a predetermined frequency, the transducer comprising:
• a piezoelectric stack positioned along the longitudinal axis;
• a first metallic end mass positioned along the longitudinal axis adjacent a first end of the piezoelectric stack;
• a second metallic end mass positioned along the longitudinal axis adjacent a second end of the piezoelectric stack, wherein the amplitude gain of the transducer is equal to one;
• and
• an end effector extending along the longitudinal axis coupled to the transducer, wherein the end effector comprises:
• a plurality of first sections positioned along the longitudinal axis having a first diameter;
• a plurality of second sections positioned along the longitudinal axis between the plurality of first sections, wherein the plurality of second sections have a second diameter larger than the first diameter, wherein at least a portion of distally facing ends of the plurality of second sections are located at a first plurality of zero-displacement nodes, wherein at least a portion of proximally facing ends of the second sections are located at a second plurality of zero-displacement nodes, and wherein the first plurality and the second plurality of zero-displacement nodes do not include any zero-displacement nodes in common.