Influence of oscillating features of a laser-induced bubble on laser propulsion in water environment near different interfaces

School of Science, Nanjing University of Science & Technology, Nanjing, 210094, P.R. China

Corresponding author: h.chenjun86@gmail.com

Received: 20 May 2010
Revised: 13 July 2010
Accepted: 24 August 2010
Published online: 30 November 2010

Abstract

Laser propulsion in a water environment is influenced by oscillating features of a laser-induced bubble. In our study an optical beam deflection method is used to investigate dynamics of laser-induced semispherical cavitation bubbles near three different interfaces: the rigid boundary (water-solid interface), the free surface (water-air interface) and the liquid-liquid interface (water-soybean oil interface), and in the bulk. The maximum radius of the first bubble oscillation R_max1 was widened and the collapse time T₁ is prolonged in the case of the rigid boundary. R_max1 is diminished and T₁ is shortened in the case of the free surface and the water-oil interface, among which the latter makes R_max1 even smaller. In order to get the maximum propelling force in different distances near different medium interfaces, different pulse energy of the laser is used. The bubble moves toward the rigid boundary and moves away from the free surface during its oscillations. This will change the application point of the propelling force on the object, and cause a change in the propelling direction of the object.