A laser induced cavitation pump

We demonstrate and discuss a liquid pumping effect based on the interaction between periodically generated cavitation microbubbles and a millimeter diameter tube. The bubbles are generated by the heat of laser adsorption at the tip of an optical fiber immersed in liquid. When the bubbles are generated well away from the tube, a steady streaming flow with a relatively large and energetic ring vortex is observed. Coaxial placement of the fiber within the tube, with the fiber tip near one end of the tube, results in relatively weak pumping of liquid. In contrast, placement of the fiber outside the tube with a similar fiber tip position results in a synergetic and strong pumping effect. This paper presents quantitative measures of pumping performance as a function of relevant parameters including the axial fiber tip position, fiber orientation and laser duty cycle.