Microdroplet target synthesis for kilohertz ultrafast lasers

We have developed a method for producing spatially stable micron-scale liquid targets of flexible shapes at kilohertz repetition rate for use in air and vacuum, by perturbing 5 and $30μm$ diameter streams with femtosecond laser pulses and monitoring the temporal development of the perturbation. Using water, we have produced features such as $2.1μm$ diameter droplet and $1.3μm$ diameter neck with less than $±0.3μm$ shot-to-shot variation, with prospects for further reduction in size and variability. The use of such micron-scale targets can be expected to prevent conductive heat dissipation, enhance field strength for ion acceleration and allow spatially-deterministic laser-cluster experiments.