A multi-beam ultrasound device with intersecting beams is presented for use in medical therapy and industry. Multiple ultrasound beams interfere constructively and destructively depending on their phase at the target tissue, and this device and its methodology uses phase control for intensity enhancement at the beam intersection. Two among many embodiments are detailed: phase matching where the phases of the beams are determined and controlled to be equal, and phase sweeping where the phases of the beams are purposely varied.