The capillary breakup of multiple molten oxide jets was investigated. A graphite nozzle head allowed producing an array of laminar slag jets which disintegrate into droplets due to the growth of instabilities. A high temperature furnace with optical access and a pressurized crucible was used to generate the coherent circular jets which were recorded using a high-speed camera. External perturbations by means of a pneumatic vibrator were applied to investigate the impact of the vibration frequency on the length of each jet strand, the drop formation rate, the spacing between consecutive droplets and the drop size distribution. Results show excellent consistency in droplet formation when external vibration is applied and very good agreement with theoretical predictions. The findings may be used to facilitate the design of a droplet heat exchanger in which the latent heat of a molten slag can be transferred to a counter-current gas in a predictable manner.