Pressure wave generator and controller for generating a pressure wave in a medium

A pressure wave generator for generating a pressure wave in a medium, the pressure wave generator comprising:

• a movable piston;
• a control rod coupled to the piston;
• a transducer configured to be coupled to the medium;
• a housing having an inner bore, a first end, and a second end, the movable piston and at least a portion of the control rod disposed in the inner bore of the housing, the transducer slideably accommodated in an opening at the second end of the housing, the inner bore comprising a first cavity between the first end and the movable piston and a second cavity between the movable piston and the transducer, wherein the first cavity is configured to receive a fluid for applying fluid pressure to the movable piston to accelerate the movable piston toward the transducer, and wherein the movable piston is configured to move within the second cavity toward the transducer;
• a position sensor configured to generate a position signal representing a position of the movable piston;
• a controller operatively coupled to the position sensor, wherein the controller is configured to generate a control signal based at least in part on the position signal;
• and
• a brake operatively coupled to the controller, the brake configured to apply a restraining force to the control rod in response to the control signal such that the movable piston impacts the transducer at a desired time and with a desired kinetic energy,
• wherein the movable piston and the transducer are configured to at least partially convert the kinetic energy of the movable piston into a pressure wave in the medium upon impact of the movable piston with the transducer.