Axisymmetric Explosions in a Liquid Microjet Induced by Co-axial Nanosecond Laser

We report an experimental investigation on the explosion of a liquid microjet induced by nanosecond laser. The jet is periodically perturbed by a piezoelectric actuator to generate highly controllable jet pinch-off. The laser is introduced co-axially and propagates through the liquid jet by total internal reflections. The pinch-off region serves as a light funnel to confine and concentrate the laser beam, and the optical power flux may exceed the threshold to induce plasmas and explosions. The explosive phenomenon evolves over four different time scales spanning from 10 ns to 100 μs. The growth of the explosion gap is logarithmic while the growth of the mist plume diameter is linear with respect to time, both of which can be described by a model relating plasma volume to absorbed energy.