title: Direct Self-Sustained Fragmentation Cascade of Reactive Droplets.
abstract: A traditional hand-held firework generates light streaks similar to branched pine needles, with ever smaller ramifications. These streaks are the trajectories of incandescent reactive liquid droplets bursting from a melted powder. We have uncovered the detailed sequence of events, which involve a chemical reaction with the oxygen of air, thermal decomposition of metastable compounds in the melt, gas bubble nucleation and bursting, liquid ligaments and droplets formation, all occurring in a sequential fashion. We have also evidenced a rare instance in nature of a spontaneous fragmentation process involving a direct cascade from big to smaller droplets. Here, the self-sustained direct cascade is shown to proceed over up to eight generations, with well-defined time and length scales, thus answering a century old question, and enriching, with a new example, the phenomenology of comminution.
authors.affiliation: The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Inoue
authors.affiliation: Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
authors.forename: Yu-Ichiro
authors.initials: YI
authors.lastname: Izato
authors.affiliation: Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
authors.forename: Atsumi
authors.initials: A
authors.lastname: Miyake
authors.affiliation: Aix-Marseille University, CNRS, Centrale Marseille, IRPHE, 13013 Marseille, France.|Institut Universitaire de France, 75005 Paris, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Villermaux